refactor: Use override for non-final overriders

src/qt/overviewpage.cpp

@@ -35,7 +35,7 @@ public:
     }
 
     inline void paint(QPainter *painter, const QStyleOptionViewItem &option,
-                      const QModelIndex &index ) const
+                      const QModelIndex &index ) const override
     {
         painter->save();
 
@@ -99,7 +99,7 @@ public:
         painter->restore();
     }
 
-    inline QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const
+    inline QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const override
     {
         return QSize(DECORATION_SIZE, DECORATION_SIZE);
     }