nsswitch: Fix wbcListGroups test
With an AD DC, wbcListGroups returns the users in the DOMAIN SEPARATOR
GROUPNAME format. The test then calls wbcLookupName with the domain
name and the previous string (including domain and separator) as
username. Fix this by passing the correct username and adding some
additional checks.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=13312
Signed-off-by: Christof Schmitt <cs@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>
(cherry picked from commit
f4db4e86c341a89357082e81e30c302440647530)