[mutter] prefs: Allow no-op listener removal

[Jonas Ådahl <jadahl src gnome org>]

commit 14d8aec4b881de7126447f71fc6d1e43b22c488a
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Jun 29 19:11:50 2018 +0200

    prefs: Allow no-op listener removal
    
    Allow removing a prefs handler that was already removed. This allows us
    to remove prefs from the dispose function without having to keep track
    of it in every place.

 src/core/prefs.c | 2 --
 1 file changed, 2 deletions(-)
---
diff --git a/src/core/prefs.c b/src/core/prefs.c
index b6a8ab7bf..bad54cbf2 100644
--- a/src/core/prefs.c
+++ b/src/core/prefs.c
@@ -860,8 +860,6 @@ meta_prefs_remove_listener (MetaPrefsChangedFunc func,
 
       tmp = tmp->next;
     }
-
-  meta_bug ("Did not find listener to remove\n");
 }
 
 static void