s3: auth: Use wbcAuthenticateUserEx to prime the caches.

s3: auth: Use wbcAuthenticateUserEx to prime the caches.

Idea by Volker - use WBC_AUTH_USER_LEVEL_PAC to pass
the PAC to winbind from smbd on auth, this allows
winbind to prime the user info via netsamlogon_cache_store()
and the name2sid cache *before* smbd looks up the user.

Note that as this is merely a cache prime having
winbind not available is not an error.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11259

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Günther Deschner <gd@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Wed Sep 28 22:45:27 CEST 2016 on sn-devel-144