ScxmlEditor: Use override consistently

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

Change-Id: I636077ee65961a797677ecab39741870470566e0
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/plugins/scxmleditor/outputpane/outputtabwidget.h

@@ -75,7 +75,7 @@ class OutputTabWidget : public QFrame
 
 public:
     explicit OutputTabWidget(QWidget *parent = nullptr);
-    ~OutputTabWidget();
+    ~OutputTabWidget() override;
 
     int addPane(OutputPane *pane);
     void showPane(OutputPane *pane);

src/plugins/scxmleditor/plugin_interface/stateitem.h

@@ -62,7 +62,7 @@ public:
     void updateAttributes() override;
     void updateEditorInfo(bool allChildren = false) override;
     void updateColors() override;
-    virtual void doLayout(int d) override;
+    void doLayout(int d) override;
     void shrink();
     void setInitial(bool initial);
     bool isInitial() const;

src/plugins/scxmleditor/scxmleditordata.h

@@ -47,7 +47,7 @@ class ScxmlEditorData : public QObject
     Q_OBJECT
 public:
     ScxmlEditorData(QObject *parent = nullptr);
-    ~ScxmlEditorData();
+    ~ScxmlEditorData() override;
 
     void fullInit();
     IEditor *createEditor();