Qt4 playlist: fix crash when deleting nodes and their children

This patch fixes the crash when a node is selected together with it's children and then deleted
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

modules/gui/qt4/components/playlist/playlist_model.cpp

@@ -738,6 +738,7 @@ void PLModel::doDelete( QModelIndexList selected )
                 recurseDelete( item->children, &selected );
             doDeleteItem( item, &selected );
         }
+        if( i > selected.size() ) i = selected.size();
     }
 }