QmlJsEditor/QmlJsTools: Use override consistently

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

Change-Id: I29716dcf73946b5762568d349a3f5a3da4f656e6
Reviewed-by: Marco Benelli <marco.benelli@qt.io>

src/plugins/qmljseditor/qmljsfindreferences.h

@@ -65,7 +65,7 @@ public:
 
 public:
     FindReferences(QObject *parent = 0);
-    virtual ~FindReferences();
+    ~FindReferences() override;
 
 signals:
     void changed();