size and count limit for slapo-constraint (patch included)

ftp.openldap.org has not enough room for me to upload the patch, so I'll make the ITS later.

Here is it: http://ftp.espci.fr/shadow/manu/manu-20080430.patch

Both size and count limit on attributes work, I tested various situations. There is just a bit I'm not sure about: + op->o_bd = on->on_info->oi_origdb; + rc = be_entry_get_rw( op, &op->o_req_ndn, NULL, NULL, 0, &target_entry ); + op->o_bd = be;

Is it the way I'm supposed to get an entry for which I have a DN? It works, but it might be suboptimal.