Qt: enable the recents menu again after adding an element

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 60cff20c351db4bde6eb6ed5696fce92d54bc3bb)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/menus.cpp

@@ -1549,6 +1549,7 @@ void VLCMenuBar::updateRecents( intf_thread_t *p_intf )
 
             recentsMenu->addSeparator();
             recentsMenu->addAction( qtr("&Clear"), rmrl, SLOT( clear() ) );
+            recentsMenu->setEnabled( true );
         }
     }
 }