CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: support "server require schannel...

CVE-2020-1472(ZeroLogon): s3:rpc_server/netlogon: support "server require schannel:WORKSTATION$ = no"

This allows to add expections for individual workstations, when using "server schannel = yes".
"server schannel = auto" is very insecure and will be removed soon.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14497

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

Signed-off-by: Günther Deschner <gd@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Gary Lockyer <gary@catalyst.net.nz>