QDockWidget: Delay-create QWidgetResizeHandler.

Task-number: QTBUG-34352
Change-Id: Ia7e5d8038b334686bedeee60c35656f3ab948e4c
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Implement QWidget::grabCursor(const QCursor&).

Implement using QGuiApplication::setOverrideCursor().

Task-number: QTBUG-39311
Change-Id: I83e289bfd5e911c31f08df9a4fc17fb8a0cf27f2
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Add fixme-comment to QWidgetResizeHandler.

Task-number: QTBUG-34352
Change-Id: I2415bdf125f90f5cd4f5af55e7ec6bb8ef48217e
Reviewed-by: J-P Nurmi <jpnurmi@digia.com>
Ensure that QTemporaryFile clears all file mappings.

Factor out code to clear all mappings into
QFSFileEnginePrivate::unmapAll() and call that
from QTemporaryFile.

Task-number: QTBUG-39976
Change-Id: Ic1ceeba0ba4451866f1081fee430e5c458c0819d
Reviewed-by: Jonathan Liu <net147@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>