[metacity] stack-tracker: fix cast-function-type warning

[Alberts Muktupāvels <muktupavels src gnome org>]

commit eec826a4f47d824f0d6934abffdf721678f19bd3
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Sep 2 14:14:41 2018 +0300

    stack-tracker: fix cast-function-type warning

 src/core/stack-tracker.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
---
diff --git a/src/core/stack-tracker.c b/src/core/stack-tracker.c
index 922801f2..8265ce2c 100644
--- a/src/core/stack-tracker.c
+++ b/src/core/stack-tracker.c
@@ -479,8 +479,7 @@ meta_stack_tracker_free (MetaStackTracker *tracker)
   if (tracker->predicted_stack)
     g_array_free (tracker->predicted_stack, TRUE);
 
-  g_queue_foreach (tracker->unverified_predictions, (GFunc)meta_stack_op_free, NULL);
-  g_queue_free (tracker->unverified_predictions);
+  g_queue_free_full (tracker->unverified_predictions, (GDestroyNotify) meta_stack_op_free);
   tracker->unverified_predictions = NULL;
 
   g_free (tracker);