Use #pragma warning(push) and pop to control our warnings

Using "default" means "reset to default compiler settings", not "revert
to command-line settings". And even if it did, it's possible some other
headers by the user toggled the settings. We shouldn't affect that.

Task-number: QTBUG-35622
Change-Id: If7c4bd0cc8c210f88ee89e3fa2dd3b7194ad77bb
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Use the short time format of the current locale on Windows

Windows 7 and later have LOCALE_SSHORTTIME, which is what we need.

Task-number: QTBUG-33718
Change-Id: I4c3f113d17102a37fb752de56f06b312f27c7887
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>