ci: Add the targets/ subdirectory to facilitate cross-platform testing

Considering that a non-trivial amount of libpng code is arch-specific,
we should perform cross-platform builds (with cross-platform toolchains)
and test runs (on emulated architectures) in our routine verification.

The content of ci/targets/ shall consist of target description files,
written in the standard shell language. These files may be source'd as
needed, before running the verification scripts ci/ci_verify_*.sh.

Here is the initial list of target systems:
Android, Cygwin, FreeBSD, Linux, MSDOS, Windows.

And here is the initial list of target architectures:
ARM, MIPS, PowerPC, RISC-V, x86.

ci/targets/android/ci_env.aarch64-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_ARCHVER=aarch64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.armv7a-linux-androideabi.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_ARCHVER=armv7a
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=androideabi
+export CI_TARGET_ABIVER=androideabi29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.i686-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_ARCHVER=i686
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/android/ci_env.x86_64-linux-android.sh

@@ -0,0 +1,16 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_ARCHVER=x86_64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=android
+export CI_TARGET_ABIVER=android29
+
+export CI_CC="$CI_TARGET_ARCHVER-$CI_TARGET_SYSTEM-$CI_TARGET_ABIVER-clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"

ci/targets/cygwin/ci_env.i686-pc-cygwin.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=cygwin
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=CYGWIN
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/cygwin/ci_env.x86_64-pc-cygwin.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=cygwin
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=CYGWIN
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/darwin/ci_env.arm64-apple-darwin.sh

@@ -0,0 +1,15 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm64
+export CI_TARGET_SYSTEM=darwin
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Darwin
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+    -DCMAKE_OSX_ARCHITECTURES=$CI_TARGET_ARCH
+"

ci/targets/darwin/ci_env.x86_64-apple-darwin.sh

@@ -0,0 +1,15 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=darwin
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Darwin
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+    -DCMAKE_OSX_ARCHITECTURES=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.aarch64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.i686-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.riscv64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=riscv64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/freebsd/ci_env.x86_64-unknown-freebsd.sh

@@ -0,0 +1,14 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=freebsd
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=FreeBSD
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.aarch64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.arm-linux-gnueabi.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnueabi
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.arm-linux-gnueabihf.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=arm
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnueabihf
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.i686-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips64-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mips64el-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mips64el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsel-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsel
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa32r6-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa32r6
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa32r6el-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa32r6el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa64r6-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa64r6
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.mipsisa64r6el-linux-gnuabi64.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=mipsisa64r6el
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnuabi64
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.powerpc64le-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=powerpc64le
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.riscv64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=riscv64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/linux/ci_env.x86_64-linux-gnu.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=linux
+export CI_TARGET_ABI=gnu
+
+export CI_GCC="${CI_GCC-gcc}"
+
+export CI_CC="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-$CI_GCC"
+export CI_AR="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ar"
+export CI_RANLIB="$CI_TARGET_ARCH-$CI_TARGET_SYSTEM-$CI_TARGET_ABI-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Linux
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/msdos/ci_env.i386-pc-msdoswatcom.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i386
+export CI_TARGET_SYSTEM=msdoswatcom
+
+export CI_CC="wcl386"
+
+# Open Watcom V2 CMake build
+# https://github.com/open-watcom/open-watcom-v2/discussions/716
+export CI_CMAKE_GENERATOR="Watcom WMake"
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=DOS
+"

ci/targets/msdos/ci_env.i586-pc-msdosdjgpp.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i586
+export CI_TARGET_SYSTEM=msdosdjgpp
+
+export CI_CC="$CI_TARGET_ARCH-pc-$CI_TARGET_SYSTEM-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Generic
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/msdos/ci_env.i86-pc-msdoswatcom.sh

@@ -0,0 +1,19 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i86
+export CI_TARGET_SYSTEM=msdoswatcom
+
+export CI_CC="wcl"
+
+# Open Watcom V2 CMake build
+# https://github.com/open-watcom/open-watcom-v2/discussions/716
+export CI_CMAKE_GENERATOR="Watcom WMake"
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=DOS
+    -DCMAKE_SYSTEM_PROCESSOR=I86
+"

ci/targets/windows/ci_env.aarch64-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=aarch64
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.i686-w64-mingw32.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=mingw32
+
+# The output of `uname -s` on MSYS2 is understandable, and so is
+# CI_TARGET_SYSTEM above, in simplified form. (See also Cygwin.)
+# But aside from that, the Mingw-w64 nomenclature is rather messy.
+export CI_CC="$CI_TARGET_ARCH-w64-mingw32-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.i686-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=i686
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.x86_64-w64-mingw32.sh

@@ -0,0 +1,21 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=mingw64
+
+# The output of `uname -s` on MSYS2 is understandable, and so is
+# CI_TARGET_SYSTEM above, in simplified form. (See also Cygwin.)
+# But aside from that, the Mingw-w64 nomenclature is rather messy.
+export CI_CC="$CI_TARGET_ARCH-w64-mingw32-gcc"
+export CI_AR="$CI_CC-ar"
+export CI_RANLIB="$CI_CC-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"

ci/targets/windows/ci_env.x86_64-windows-llvm.sh

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-2024 Cosmin Truta.
+#
+# Use, modification and distribution are subject to the MIT License.
+# Please see the accompanying file LICENSE_MIT.txt
+#
+# SPDX-License-Identifier: MIT
+
+export CI_TARGET_ARCH=x86_64
+export CI_TARGET_SYSTEM=windows
+
+export CI_CC="clang"
+export CI_AR="llvm-ar"
+export CI_RANLIB="llvm-ranlib"
+
+export CI_CMAKE_VARS="
+    -DCMAKE_SYSTEM_NAME=Windows
+    -DCMAKE_SYSTEM_PROCESSOR=$CI_TARGET_ARCH
+"