libsmb: provide authinfo domain for DFS referral auth

libsmb: provide authinfo domain for DFS referral auth

libsmbclient uses the smbc_init->smbc_get_auth_data_fn() provided
workgroup/domain in initial connections, but then switches to the
default smb.conf workgroup/domain when handling DFS referrals.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=11059

Signed-off-by: David Disseldorp <ddiss@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
(cherry picked from commit 6c9de0cd056afc0b478c02f1bdb0e06532388037)
[ddiss@samba.org: 4.2 rebase with cli_init_creds() call]