libobs: Remove unused variable

libobs/obs-scene.c

@@ -2740,7 +2740,6 @@ void obs_sceneitem_group_add_item(obs_sceneitem_t *group, obs_sceneitem_t *item)
 
 	obs_scene_t *scene = group->parent;
 	obs_scene_t *groupscene = group->source->context.data;
-	obs_sceneitem_t *last;
 
 	if (item->parent != scene)
 		return;