Qt: remove a suspicious delete

in Qt doc about QMainWindow, about statusBar() and setStatusBar(), it reads :
"Note that QMainWindow takes ownership of the statusbar pointer
and deletes it at the appropriate time."
So, trying to delete the pointer returned by statusBar() can but
end up in a double free at some point.

modules/gui/qt4/main_interface.cpp

@@ -304,8 +304,6 @@ MainInterface::~MainInterface()
     /* Save this size */
     QVLCTools::saveWidgetPosition(settings, this);
 
-    delete statusBar();
-
     /* Unregister callbacks */
     var_DelCallback( p_intf->p_libvlc, "intf-boss", IntfBossCB, p_intf );
     var_DelCallback( p_intf->p_libvlc, "intf-show", IntfRaiseMainCB, p_intf );