Fixed a compiler warning about the destructor of GOOrgancontroller GrandOrgue#2001

Author: oleg68

src/grandorgue/GOOrganController.h

@@ -130,7 +130,7 @@ class GOOrganController : public GOEventDistributor,
     GOConfig &config,
     GOMidiDialogCreator *pMidiDialogCreator = nullptr,
     bool isAppInitialized = false);
-  ~GOOrganController();
+  virtual ~GOOrganController();
 
   GOSizeKeeper &GetStopWindowSizeKeeper() { return m_StopWindowSizeKeeper; }