Qt Creator currently must compile with both Qt 4 and Qt 5, so we can't
change the code to call the non-deprecated functions that have been
recently deprecated in Qt 5, unless those functions already existed.

This change asks Qt 5 to enable the use of pre-5.0 API without warnings.

Change-Id: Ic165336f40d15fe5793d30bb9262986f738c984e
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>