Clean up CInterfaceAGL, make sure the screen gets cleared on stop, and remove the FPS update that messes up GUI builds since GUIless doesn't build anyways.

Source/Core/DolphinWX/Src/GLInterface/AGL.h

@@ -28,7 +28,6 @@ class cInterfaceAGL : public cInterfaceBase
 {
 public:
 	void Swap();
-	void UpdateFPSDisplay(const char *Text);
 	bool Create(void *&window_handle);
 	bool MakeCurrent();
 	void Shutdown();