s3:winbindd: fix _wbint_LookupSids() on error

s3:winbindd: fix _wbint_LookupSids() on error

We need to make sure that r->out.domains remains valid,
otherwise we're not able to marshall the response.

Note that wbint_LookupSids() has [out,ref] lsa_RefDomainList *domains,
while lsa_LookupSids() has [out,ref] lsa_RefDomainList **domains.

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>

Bug: https://bugzilla.samba.org/show_bug.cgi?id=10458
Signed-off-by: Gregor Beck <gbeck@sernet.de>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Andreas Schneider <asn@samba.org>