Fix QSysInfo::windowsVersion() on WinCE

Use the GetVersionEx method on WinCE. The ntdll.dll does not
exist on that platform, therefor a wrong version number was returned.

Change-Id: I7b51757d0fb612dcd8832e0903a93b9d1c6746c0
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Andreas Holzammer <andreas.holzammer@kdab.com>