Replaced some linux includes with <private/qcore_unix_p.h> to be more
portable.
Use qt_safe_open() and qt_safe_close() instead of ::open() and
::close().
Task-number: QTBUG-38061
Change-Id: Idb3f50d070ec1701cafba98e79e2e85824653a3a
Reviewed-by: Lisandro Damián Nicanor Pérez Meyer <perezmeyer@gmail.com>
Reviewed-by: Christian Stromme <christian.stromme@digia.com>