Previous commit b2363a935c fixed keyboardModifiers() after QPA event
processing, but broke QTestLib, which expects spontaneous input events
sent to qApp->notify() to update keyboardModifiers() and mouseButtons().
The commit also did not fix mouseButtons() after QPA event processing,
and missed keyboardModifiers() after QPA Tablet event processing.
This commit fixes all these shortcommings in b2363a935c.
Includes test case by David Faure <faure@kde.org>
Task-Number: QTBUG-26887
Change-Id: I8518b06c4ce86ea7b35120e3353a45ea2a81d356
Reviewed-by: David Faure (KDE) <faure@kde.org>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
cf2a75e41b