GLSL: Promote HLSL entry-point renaming code to be used by GLSL as well.

Fixes #1045.

glslang/MachineIndependent/glslang.y

@@ -860,6 +860,11 @@ function_header
         // Add the function as a prototype after parsing it (we do not support recursion)
         TFunction *function;
         TType type($1);
+
+        // Potentially rename shader entry point function.  No-op most of the time.
+        parseContext.renameShaderFunction($2.string);
+
+        // Make the function
         function = new TFunction($2.string, type);
         $$ = function;
     }