Fix warning about overriding virtual method

Fix warning about overriding virtal method QAbstractItemView::openEditor
in openeditorsview.

Change-Id: Ice413270dca4fe36f7c033992532498424381202
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/coreplugin/editormanager/openeditorsview.h

@@ -70,6 +70,7 @@ private slots:
 private:
     void activateEditor(const QModelIndex &index);
     void closeEditor(const QModelIndex &index);
+    using QAbstractItemView::closeEditor;
 
     OpenEditorsDelegate *m_delegate;
 };