Support OpenLDAP 2.5+
For context see:
https://bugzilla.redhat.com/show_bug.cgi?id=2150344 https://github.com/EGI-Federation/bdii/pull/42 https://github.com/EGI-Federation/bdii/issues/41
Fixes infosys-ldap om EPEL 9, Fedora 36+ and others with OpenLDAP 2.5+.