Implement the extension GL_EXT_spirv_intrinsics

- Add support of SPIR-V execution mode qualifiers.
- Add support of SPIR-V storage class qualifier.
- Add support of SPIR-V decorate qualifiers.
- Add support of SPIR-V type specifier.
- Add support of SPIR-V intruction qualifiers.
- Add support of spirv_by_reference/spirv_literal parameter qualifier.
- Add shader stage macros introduced by this extension.

Test/spv.intrinsicsSpirvExecutionMode.frag

@@ -0,0 +1,17 @@
+#version 450 core
+
+#extension GL_EXT_spirv_intrinsics: enable
+
+#define GL_ARB_shader_stencil_export 1
+
+spirv_execution_mode(5027); // StencilRefReplacingEXT
+
+spirv_decorate(extensions = ["SPV_EXT_shader_stencil_export"], capabilities = [5013], 11, 5014)
+out int gl_FragStencilRef;
+
+layout(location = 0) in flat int color;
+
+void main()
+{
+    gl_FragStencilRef = color;
+}