s4:dsdb: add support for DSDB_OPENLDAP_DEREFERENCE_CONTROL
Encode and decode the OpenLDAP dereference control (draft-masarati-ldap-deref-00)
At this time, the ldb_controls infrustructure does not handle request
and reply controls having different formats, so this is purely the
client implementation (ie, there is no decode of the client->server
packet, and no encode of the server->client packet).
Signed-off-by: Stefan Metzmacher <metze@samba.org>