rules use that directory to lookup users & groups as opposed to the
host system's passwd(5) and group(5) databases.
This is a change of behaviour which should make the build system more
robust when new users & groups are added to the NetBSD source.
The only users who may be adversely affected are those (small number,
if any) that renumber the uids & gids away from the "standard" NetBSD
ones; in this case said users should maintain local mods to
${NETBSDSRCDIR}/etc/{master.passwd,group} ...