r23406: Evn if not strictly currently necessary do check for correct

r23406: Evn if not strictly currently necessary do check for correct
init also in idmap_nss and idmap_passdb for coherency and to
prevent errors in future if we change the init functions to
actually do something and not just return NT_STATUS_OK
(This used to be commit 86f532c1b0cf7961b8331bb212c3ed2084fda3fc)