This reverts commit 6b5bbc531b.
Autograbbing mouse shouldn't be done in crossplatform code, as
X11 does this automatically. Windows needs platform specific
solution.
Task-number: QTBUG-26962
Task-number: QTBUG-27039
Task-number: QTBUG-23699
Change-Id: I911df92c4a34deb50b729f50681497046657948b
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>