* security.cc (extract_nt_dom_user): Simplify with strechr.
(get_user_groups): Initialize glen to MAX_SID_LEN.
(get_user_local_groups): Ditto.
(get_attribute_from_acl): Define ace_sid as cygpsid.
(get_nt_attribute): Define owner_sid and group_sid as cygpsid.
Call get_sids_info instead of cygsid.get_{u,g}id and is_grp_member.
(get_nt_object_attribute): Ditto.
(alloc_sd): Define ace_sid as cygpsid.