Fixes a compiler warning with -Wmaybe-uninitialized enabled:
../../../../Source/gnome/mutter/clutter/clutter/clutter-actor.c: In function ‘clutter_actor_paint’:
../../../../Source/gnome/mutter/clutter/clutter/clutter-actor.c:3808:50: warning: ‘result’ may be used uninitialized in this function [-Wmaybe-uninitialized]
3808 | else if (result == CLUTTER_CULL_RESULT_OUT && success)
| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
Which might presumably happen in the unlikely case that there's no clip
frusta.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1624>
14ab90eeba