Windows: kauth search for kerberos iv port first

Windows: kauth search for kerberos iv port first

Modify src/kauth/user_nt.c to match the service name search
order of the Unix code:

 kerberos4
 kerberos-iv
 kerberos

The standard Windows SERVICES file includes "kerberos-iv" as
port 750.

FIXES 127907

Change-Id: I518a812cc2d465334e8ef6929f8988c51b33749b
Reviewed-on: http://gerrit.openafs.org/6430
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>