Windows: afslogon.dll vs windows 7

Windows: afslogon.dll vs windows 7

In Windows 7 the GINA is no longer used.  As a result, when a
non-Heimdal realm is used for logon, the LogonDomain field
is no longer populated during the NPLogonNotify call.  Instead
we must obtain the Kerberos realm from the UPN specified in
the Username field.

Change-Id: I838e0a5b19d560dd2fed6ccccf1e136fe1c4e0c2
Reviewed-on: http://gerrit.openafs.org/1660
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>