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.

src/osx/utils_osx.cpp

@@ -183,26 +183,7 @@ wxWindow* wxFindWindowAtPoint(wxWindow* win, const wxPoint& pt);
 
 wxWindow* wxFindWindowAtPoint(const wxPoint& pt)
 {
-#if wxOSX_USE_CARBON
-
-    Point screenPoint = { pt.y , pt.x };
-    WindowRef windowRef;
-
-    if ( FindWindow( screenPoint , &windowRef ) )
-    {
-        wxNonOwnedWindow *nonOwned = wxNonOwnedWindow::GetFromWXWindow( windowRef );
-
-        if ( nonOwned )
-            return wxFindWindowAtPoint( nonOwned , pt );
-    }
-
-    return NULL;
-
-#else
-
     return wxGenericFindWindowAtPoint( pt );
-
-#endif
 }
 
 /*