Remove wxOSX/Carbon support.

Cocoa has been the default toolkit in wxWidgets for a long time. There is really no good reason to use Carbon in 2016 and this removes a lot of unused and unmaintained code.

include/wx/osx/sound.h

@@ -34,16 +34,6 @@ public :
     // does the true work of stopping and cleaning up
     virtual void DoStop() = 0;
 
-#if wxOSX_USE_CARBON
-    // can be called by a timer for repeated tasks during playback
-    virtual void SoundTask();
-
-protected :
-    void CreateAndStartTimer();
-
-    wxSoundTimer* m_pTimer;
-#endif // wxOSX_USE_CARBON
-
 protected:
     unsigned int m_flags;
     bool m_markedForDeletion;