this fixes the problem of not being able to add a SD to a file on a

this fixes the problem of not being able to add a SD to a file on a
non-domain Samba server from a NT4 client.

Note that this exactly reverses a change by Jeremy on the 18th of
December 2001, reverting the code back to what JF originally wrote. I
have looked carefully with a sniffer and JFs original NULL sid is
correct (ie. it matches what NT4 does) and also fixes the problem.

Sending a blank sid (which is what jeremy's patch did) causes NT4 to
give a classic "parameter is incorrect error" and prevents the
addition of new ACLs.
(This used to be commit 9930cf97330dd93985c5558cec6b24406e90c228)