Only allow clearing playlist if current item can be edited

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>
(cherry picked from commit 4f771d1d)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

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

@@ -978,8 +978,10 @@ bool PLModel::popup( const QModelIndex & index, const QPoint &point, const QMode
 
     menu.addSeparator();
 
-    menu.addAction( QIcon( ":/toolbar/clear" ), qtr("Clear playlist"),
-                    this, SLOT( clearPlaylist() ) );
+    if( canEdit() ) {
+        menu.addAction( QIcon( ":/toolbar/clear" ), qtr("Clear playlist"),
+                        this, SLOT( clearPlaylist() ) );
+    }
 
     /* Playlist sorting */
     if( !sortingMenu )