Base: modernize C++: use override

src/Base/Builder3D.h

@@ -646,7 +646,7 @@ class BaseExport Builder3D : public InventorBuilder
 {
 public:
     Builder3D();
-    virtual ~Builder3D();
+    ~Builder3D() override;
 
     /// clear the string buffer
     void clear();

src/Main/FreeCADGuiPy.cpp

@@ -65,7 +65,7 @@ public:
     QtApplication(int &argc, char **argv)
         : QApplication(argc, argv) {
     }
-    bool notify (QObject * receiver, QEvent * event) {
+    bool notify (QObject * receiver, QEvent * event) override {
         try {
             return QApplication::notify(receiver, event);
         }