Ticket 47372 - make old-idl tunable
Bug Description: With the change from ticket 47326 old-idl is working, but tests
showed that performance heavily depends on the size of the idlists.
So idl_maxids should be made configurable.
Fix Description: Added a new config ldbm config setting, "nsslapd-old-idl-maxids".
If this is not set, which is the default value, then we calulate it
the old way, otherwise the config setting is used.
https://fedorahosted.org/389/ticket/47372
Reviewed by: ?