Added initial tests for --glsl-version

- Added compilation tests for shader stages using a different
  version at each stage.

Test/glsl.versionOverride.comp

@@ -0,0 +1,11 @@
+/*
+
+glslangValidator.exe --glsl-version 460 -V -S comp -o glsl.versionOverride.comp.out glsl.versionOverride.comp
+
+*/
+
+#version 330
+
+void main() 
+{
+}