Merge auth changes from HEAD:

Merge auth changes from HEAD:

 - better error codes than NT_STATUS_UNSUCCESSFUL for domain logon errors
 - make auth_winbind load the ntdomain module if winbind isn't there.
 - use new trusted domains cache to determine if the domain is valid.

Andrew Bartlett
(This used to be commit ec8d6524c6b0c70927a2b57aab71d9e3a7f8a150)