cursor-renderer: Make 'handled_by_backend' state 'needs_overlay'

This will, conceptually, and eventually, allow a backend to both want an
overlay, while still handling it by default.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2777>

src/backends/native/meta-cursor-renderer-native.c

@@ -1113,9 +1113,9 @@ meta_cursor_renderer_native_update_cursor (MetaCursorRenderer *renderer,
   schedule_sync_position (native);
   clutter_stage_schedule_update (stage);
 
-  return (priv->has_hw_cursor ||
-          !cursor_sprite ||
-          !meta_cursor_sprite_get_cogl_texture (cursor_sprite));
+  return !(priv->has_hw_cursor ||
+           !cursor_sprite ||
+           !meta_cursor_sprite_get_cogl_texture (cursor_sprite));
 }
 
 static void