Fix completely wrong logic for veto checking in generic wxDVC.

Fix completely wrong logic for veto checking in generic wxDVC.

The code sending the event must check whether the event was vetoed or not, not
whether it was skipped or not. This is the minimal change resulting in correct
behaviour even if an event handler does skip the event.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@68866 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775