Ignore wl_output globals not bound by us

Gdk doesn't know the scale of output globals it didn't bind. This
keeps them from entering the output list and triggering erroneous
changes in surface scales.

gdk/wayland/gdkwindow-wayland.c

@@ -1520,6 +1520,14 @@ surface_enter (void              *data,
 {
   GdkWindow *window = GDK_WINDOW (data);
   GdkWindowImplWayland *impl = GDK_WINDOW_IMPL_WAYLAND (window->impl);
+  GdkWaylandDisplay *display_wayland =
+    GDK_WAYLAND_DISPLAY (gdk_window_get_display (window));
+  gboolean output_is_unmanaged;
+
+  output_is_unmanaged =
+    _gdk_wayland_screen_get_output_scale (display_wayland->screen, output) == 0;
+  if (output_is_unmanaged)
+    return;
 
   GDK_NOTE (EVENTS,
             g_message ("surface enter, window %p output %p", window, output));