Add Kokoro bots for building using Bazel.

kokoro/linux-clang-release-bazel/continuous.cfg

@@ -0,0 +1,16 @@
+# Copyright (c) 2019 Google LLC.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Continuous build configuration.
+build_file: "glslang/kokoro/linux-clang-release-bazel/build.sh"