GL_ARM_shader_core_builtins support

Add support for GL_ARM_shader_core_builtins and SPV_ARM_core_builtins,
including initial tests

Test/spv.ARMCoreBuiltIns.vert

@@ -0,0 +1,12 @@
+#version 450
+#extension GL_ARM_shader_core_builtins: enable
+layout(set = 0, binding = 0, std430) buffer Output
+{
+  uvec4 result;
+};
+
+void main (void)
+{
+  uint temp = gl_WarpMaxIDARM;
+  result = uvec4(gl_CoreIDARM, gl_CoreCountARM, gl_CoreMaxIDARM, gl_WarpIDARM + temp);
+}