cursor-renderer/native: Don't trigger redraw when cursor hidden

When a cursor is hidden, the native backend will properly hide the HW
cursor sprite as well, but it would communicate this as if the cursor
was not handled by the backend, while in fact it still was. This caused
the generic cursor rendering layer to queue a redraw.

https://gitlab.gnome.org/GNOME/mutter/issues/77

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

@@ -685,7 +685,10 @@ meta_cursor_renderer_native_update_cursor (MetaCursorRenderer *renderer,
 
   priv->has_hw_cursor = should_have_hw_cursor (renderer, cursor_sprite);
   update_hw_cursor (native, cursor_sprite);
-  return priv->has_hw_cursor;
+
+  return (priv->has_hw_cursor ||
+          !cursor_sprite ||
+          !meta_cursor_sprite_get_cogl_texture (cursor_sprite));
 }
 
 static void