On MacOS the system already has user_from_uid and group_from_gid.
These are renamed pwcache_get_user and pwcache_get_group.
For the old library, pwcache_get_user needs to be exported
for skill.
References:
https://gitlab.com/procps-ng/procps/issues/34
Signed-off-by: Craig Small <csmall@enc.com.au>