GL_ARM_shader_core_builtins support

Add support for GL_ARM_shader_core_builtins and SPV_ARM_core_builtins,
including initial tests

glslang/Include/BaseTypes.h

@@ -316,6 +316,13 @@ enum TBuiltInVariable {
     EbvByteAddressBuffer,
     EbvRWByteAddressBuffer,
 
+    // ARM specific core builtins
+    EbvCoreCountARM,
+    EbvCoreIDARM,
+    EbvCoreMaxIDARM,
+    EbvWarpIDARM,
+    EbvWarpMaxIDARM,
+
     EbvLast
 };