Build fixes for OpenGL support in wxGTK with Wayland

Don't try using X-specific symbols when GDK_WINDOWING_X11 is off.

Closes https://github.com/wxWidgets/wxWidgets/pull/2191

src/gtk/window.cpp

@@ -2460,7 +2460,7 @@ wxWindow *wxGetActiveWindow()
 
 // Under Unix this is implemented using X11 functions in utilsx11.cpp but we
 // need to have this function under Windows too, so provide at least a stub.
-#ifndef GDK_WINDOWING_X11
+#ifdef GDK_WINDOWING_WIN32
 bool wxGetKeyState(wxKeyCode WXUNUSED(key))
 {
     wxFAIL_MSG(wxS("Not implemented under Windows"));