= Implement thread-safe versions of the getpwent(3) and getgrent(3)
family of functions using the new nsdispatch(3) core. Remove
arbitrary size limits when using the thread-safe versions.
= Re-implement the traditional getpwent(3)/getgrent(3) functions on
top of the thread-safe versions.
= Update the on-disk format of the hashed version of the passwd(5)
databases to allow for versioned entries. The legacy version is
`3'. (Don't ask.)
= Add support for version `4' entries in the passwd(5) database.
Entries in this format are identical to version 3 entries except
that all integers are stored as 32-bit integers in network byte
order (big endian).
= pwd_mkdb is updated to generate both version 3 and version 4
entries.