[mutter] wayland/surface: Reset buffer_destroy_handler_id

[Jonas Ådahl <jadahl src gnome org>]

commit 98892391d764d1cf4b32e57367e45f39b10880e4
Author: Robert Mader <robert mader posteo de>
Date:   Sun Oct 20 21:32:29 2019 +0200

    wayland/surface: Reset buffer_destroy_handler_id
    
    Syncronized subsurfaces that call into `merge_pending_state` might
    otherwise not create new destroy handlers, ending up with a invalid
    handler ids, throwing errors and leaking.
    
    https://gitlab.gnome.org/GNOME/mutter/merge_requests/868

 src/wayland/meta-wayland-surface.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/wayland/meta-wayland-surface.c b/src/wayland/meta-wayland-surface.c
index e10467502..5918e38d5 100644
--- a/src/wayland/meta-wayland-surface.c
+++ b/src/wayland/meta-wayland-surface.c
@@ -401,7 +401,7 @@ static void
 pending_buffer_resource_destroyed (MetaWaylandBuffer       *buffer,
                                    MetaWaylandPendingState *pending)
 {
-  g_signal_handler_disconnect (buffer, pending->buffer_destroy_handler_id);
+  g_clear_signal_handler (&pending->buffer_destroy_handler_id, buffer);
   pending->buffer = NULL;
 }