Add a new style hint to QPlatformIntegration: ReplayMousePressOutsidePopup.
Return false for it in the xcb plugin.

This commit restores the behavior which was in Qt 4.

Task-number: QTBUG-34814
Change-Id: I19fee762395a51475cc67b52b368c70679ca736b
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>