xwm: remove the create surface listener in weston_wm_destroy

Failing to remove this can result in a crash when the signal is sent
after the window manager is destroyed.

Signed-off-by: Derek Foreman <derekf@osg.samsung.com>
Reviewed-By: Giulio Camuffo <giuliocamuffo@gmail.com>

xwayland/window-manager.c

@@ -2229,6 +2229,7 @@ weston_wm_destroy(struct weston_wm *wm)
 	wl_list_remove(&wm->activate_listener.link);
 	wl_list_remove(&wm->kill_listener.link);
 	wl_list_remove(&wm->transform_listener.link);
+	wl_list_remove(&wm->create_surface_listener.link);
 
 	free(wm);
 }