[mutter/gnome-3-36] wayland: Plug XDnD drag source leak

[Robert Mader <rmader src gnome org>]

commit f5c8673ef1c56a4e309024e87752c0628b564d09
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Feb 8 20:20:22 2021 +0100

    wayland: Plug XDnD drag source leak
    
    This object is just being detached, with no code unref'ing it. Do
    this whenever the XDnD selection goes unowned, usually a good
    indication that the drag source no longer is one.
    
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1720>
    
    (cherry-picked from 8e01ea1e045c2ef1f417154c5f55360ffb14ad9e)

 src/wayland/meta-xwayland-dnd.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/wayland/meta-xwayland-dnd.c b/src/wayland/meta-xwayland-dnd.c
index f3251fc8b3..eb667fde54 100644
--- a/src/wayland/meta-xwayland-dnd.c
+++ b/src/wayland/meta-xwayland-dnd.c
@@ -907,6 +907,7 @@ meta_xwayland_dnd_handle_xfixes_selection_notify (MetaWaylandCompositor *composi
   else if (event->owner == None)
     {
       meta_xwayland_end_dnd_grab (data_device, FALSE);
+      g_clear_object (&dnd->source);
     }
 
   return FALSE;