macosx: do not leak o_fs_panel

(cherry picked from commit 79f751eb)
Signed-off-by: Derk-Jan Hartman <hartman@videolan.org>

modules/gui/macosx/controls.m

@@ -110,6 +110,7 @@
 {
     [[NSNotificationCenter defaultCenter] removeObserver: self];
     
+    [o_fs_panel release];
     [o_repeat_single release];
     [o_repeat_all release];
     [o_repeat_off release];