VP1TrackSystems: slots -> Q_SLOTS

Rename the Qt slots 'keyword' to Q_SLOTS.

Having this in the source confuses cppcheck, which reports syntax errors. We can define slots as a macro expanding to nothing in the cppcheck configuration, but if we do that globally, there are other packages that break because they use slots as an identifier. Using Q_SLOTS instead prevents this name collision.

graphics/VP1/VP1Systems/VP1TrackSystems/VP1TrackSystems/AscObjSelectionManager.h

 /*
-  Copyright (C) 2002-2022 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
 */
 
 
@@ -87,7 +87,7 @@ private:
   void unregisterAscObj(SoSeparator*simple,SoSeparator *detailed);
   //Fixme: When a handle changes pickable state to unpickable it
   //must be removed from selection list if selected!
-private slots:
+private Q_SLOTS:
 //  void ascObjDetailLevelAboutToChange();
   void ascObjDetailLevelChanged();
 private: