gdk: Disable cogl wayland event dispatching if requested

If gdk event retrieval has been disabled and gdk's backend is wayland
we must also disable cogl's wayland event dispatching otherwise cogl
will try to dispatch wayland events itself which blocks the main
loop.

https://bugzilla.gnome.org/show_bug.cgi?id=744058

clutter/gdk/clutter-backend-gdk.c

@@ -295,6 +295,7 @@ clutter_backend_gdk_get_renderer (ClutterBackend  *backend,
       /* Force a Wayland winsys */
       cogl_renderer_set_winsys_id (renderer, COGL_WINSYS_ID_EGL_WAYLAND);
       cogl_wayland_renderer_set_foreign_display (renderer, display);
+      cogl_wayland_renderer_set_event_dispatch_enabled (renderer, !disable_event_retrieval);
     }
   else
 #endif