Qt: fix a crash when using the skins

(cherry picked from commit 7a216cf685a834d038da9b474271687167c10441)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/menus.cpp

@@ -950,6 +950,7 @@ void VLCMenuBar::MiscPopupMenu( intf_thread_t *p_intf, bool show )
 {
     POPUP_BOILERPLATE
 
+    menu = new QMenu();
     if( p_input )
     {
         varnames.append( "audio-es" );
@@ -957,7 +958,6 @@ void VLCMenuBar::MiscPopupMenu( intf_thread_t *p_intf, bool show )
         menu->addSeparator();
     }
 
-    menu = new QMenu();
     Populate( p_intf, menu, varnames, objects );
 
     menu->addSeparator();