r4847: Hand over a acb_mask to pdb_setsampwent in load_sampwd_entries().

r4847: Hand over a acb_mask to pdb_setsampwent in load_sampwd_entries().

This allows the ldap-backend to search much more effeciently. Machines
will be searched in the ldap_machine_suffix and users in the
ldap_users_suffix. (Note that we already use the ldap_group_suffix in
ldapsam_setsamgrent for quite some time).

Using the specific ldap-bases becomes notably important in large
domains: On my testmachine "net rpc trustdom list" has to search through
40k accounts just to list 3 interdomain-trust-accounts, similiar effects
show up the non-user query_dispinfo-calls, etc.

Also renamed all_machines to only_machines in load_sampwd_entries()
since that reflects better what is really meant.

Guenther
(This used to be commit 6394257cc721ca739bda0e320375f04506913533)