smbd: Add smbd_smb1_do_locks_send/recv()

smbd: Add smbd_smb1_do_locks_send/recv()

This contains the SMB1-specific brlock logic. Right now our core
brlock code has specialized code to deal with pending locks. For
dealing with pending requests waiting for something nowadays we
recommend to use tevent_req. This code also provides the basis to
remove the SMB1 special case handling from the core logic, isolating
protocol features specific to SMB1 and not exposed in SMB2 in
SMB1-specific code.

The core brlock code will not see blocking locks anymore. Instead, the
code in this patch will always immediately fail and take care of the
retries and timeouts.

Retries are implemented by a dbwrap_watch_record_send on the
corresponding locking.tdb entry. A later commit will make unlocks
trigger wakeups there. I chose locking.tdb and not brlock itself to
simplify the implementation. We already have oplock break watchers on
locking.tdb, this will only add one more. This might lead to spurious
wakeups, but they are taken care of by careful retries. An advantage
of doing that is the implicit handling of a killed blocker PID through
dbwrap_watch, obsoleting brl_revalidate.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>