[mutter] stack: Fix a leak

[Florian Müllner <fmuellner src gnome org>]

commit a2ff8f4e1e200efa0704e498a7720f582a178180
Author: Florian Müllner <fmuellner gnome org>
Date:   Thu Jan 15 18:03:32 2015 +0100

    stack: Fix a leak

 src/core/stack.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/core/stack.c b/src/core/stack.c
index 037e878..09f2821 100644
--- a/src/core/stack.c
+++ b/src/core/stack.c
@@ -1137,6 +1137,7 @@ stack_sync_to_xserver (MetaStack *stack)
                    x11_stacked->len);
 
   g_array_free (x11_stacked, TRUE);
+  g_array_free (x11_hidden_stack_ids, TRUE);
   g_array_free (all_root_children_stacked, TRUE);
 }