Do not register new timers after closingDown() has been called. They
might call back into QEventDispatcherWin32 after the object has been
destructed, leading to crashes on exit.
registerSocketNotifier has a similar protection using
QCoreApplication::closingDown(). This however does not work in all cases,
because QEventDispatcher::closingDown() is called in
~QGuiApplication(), while QCoreApplication::is_app_closing is set
in ~QCoreApplication(). In between qt_call_post_routines() is called,
which might trigger new timers to be registered.
Task-number: QTBUG-42772
Change-Id: I91325fb10e38c117c1cbedfee272d0ab6a5ca8fa
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>