SPV: Turn on atomic-storage functionality for SPIR-V.

This is used by OpenGL, but not Vulkan.
Includes:
 - atomicCounter, atomicIncrement, atomicCounterDecrement
 - atomic_uint layout-offset checking
 - AtomicStorage capability

gtests/AST.FromFile.cpp

@@ -186,7 +186,6 @@ INSTANTIATE_TEST_CASE_P(
         "whileLoop.frag",
         "nonVulkan.frag",
         "negativeArraySize.comp",
-        "spv.atomic.comp",
         "precise.tesc",
         "precise_struct_block.vert",
         "maxClipDistances.vert",

gtests/Spv.FromFile.cpp

@@ -41,19 +41,29 @@
 namespace glslangtest {
 namespace {
 
-using CompileToSpirvTest = GlslangTest<::testing::TestWithParam<std::string>>;
+using CompileVulkanToSpirvTest = GlslangTest<::testing::TestWithParam<std::string>>;
+using CompileOpenGLToSpirvTest = GlslangTest<::testing::TestWithParam<std::string>>;
 using VulkanSemantics = GlslangTest<::testing::TestWithParam<std::string>>;
 using VulkanAstSemantics = GlslangTest<::testing::TestWithParam<std::string>>;
 
 // Compiling GLSL to SPIR-V under Vulkan semantics. Expected to successfully
 // generate SPIR-V.
-TEST_P(CompileToSpirvTest, FromFile)
+TEST_P(CompileVulkanToSpirvTest, FromFile)
 {
     loadFileCompileAndCheck(GLSLANG_TEST_DIRECTORY, GetParam(),
                             Source::GLSL, Semantics::Vulkan,
                             Target::Spv);
 }
 
+// Compiling GLSL to SPIR-V under OpenGL semantics. Expected to successfully
+// generate SPIR-V.
+TEST_P(CompileOpenGLToSpirvTest, FromFile)
+{
+    loadFileCompileAndCheck(GLSLANG_TEST_DIRECTORY, GetParam(),
+                            Source::GLSL, Semantics::OpenGL,
+                            Target::Spv);
+}
+
 // GLSL-level Vulkan semantics test. Expected to error out before generating
 // SPIR-V.
 TEST_P(VulkanSemantics, FromFile)
@@ -73,7 +83,7 @@ TEST_P(VulkanAstSemantics, FromFile)
 
 // clang-format off
 INSTANTIATE_TEST_CASE_P(
-    Glsl, CompileToSpirvTest,
+    Glsl, CompileVulkanToSpirvTest,
     ::testing::ValuesIn(std::vector<std::string>({
         // Test looping constructs.
         // No tests yet for making sure break and continue from a nested loop
@@ -192,6 +202,18 @@ INSTANTIATE_TEST_CASE_P(
     FileNameAsCustomTestSuffix
 );
 
+// clang-format off
+INSTANTIATE_TEST_CASE_P(
+    Glsl, CompileOpenGLToSpirvTest,
+    ::testing::ValuesIn(std::vector<std::string>({
+        // Test looping constructs.
+        // No tests yet for making sure break and continue from a nested loop
+        // goes to the innermost target.
+        "spv.atomic.comp",
+    })),
+    FileNameAsCustomTestSuffix
+);
+
 INSTANTIATE_TEST_CASE_P(
     Glsl, VulkanSemantics,
     ::testing::ValuesIn(std::vector<std::string>({