Explicitly skip system builtin inputs in GL reflection
Explicitly skip system builtin inputs in GL reflection

* Some drivers (e.g. macOS) will still return a location even for gl_.. builtins

TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,Zorro666/renderdoc,baldurk/renderdoc,Zorro666/renderdoc,Zorro666/renderdoc,googlestadia/renderdoc,baldurk/renderdoc,baldurk/renderdoc,Zorro666/renderdoc,googlestadia/renderdoc,googlestadia/renderdoc,TurtleRockStudios/renderdoc_public,baldurk/renderdoc,TurtleRockStudios/renderdoc_public,Zorro666/renderdoc,TurtleRockStudios/renderdoc_public,googlestadia/renderdoc,TurtleRockStudios/renderdoc_public,baldurk/renderdoc,Zorro666/renderdoc,googlestadia/renderdoc,baldurk/renderdoc,TurtleRockStudios/renderdoc_public