s3:winbindd: fix the valid usage anonymous smb authentication
If we are in a situation where we don't have credentials to contact the
remote domain or against an NT4 with the following settings:
workgroup = NT4DOM
security = domain
require strong key = no
client use spnego = no
client ipc signing = auto
BUG: https://bugzilla.samba.org/show_bug.cgi?id=12587
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
(cherry picked from commit
c97a29bdfdc0020ec0113073580da56f2d35edc1)