Core: Use override consistently

clang-tidy fixes from modernize-use-override check.

Change-Id: If33399d60e96cae766bbedbe30044ada411e862f
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/ioutputpane.h

@@ -43,7 +43,7 @@ class CORE_EXPORT IOutputPane : public QObject
 
 public:
     IOutputPane(QObject *parent = nullptr);
-    ~IOutputPane();
+    ~IOutputPane() override;
 
     virtual QWidget *outputWidget(QWidget *parent) = 0;
     virtual QList<QWidget *> toolBarWidgets() const = 0;