strictly necessary for the install floppy, but it enables one to
build a rescue floppy with ssh(1) on it. ssh dereferences pw->pw_class
and will therefore core dump if it is not set to something.
Reviewed By: simonb@NetBSD.ORG
to libc/gen/getpwent.c. this version reads from master.passwd instead
of passwd (thus removing the need to keep both in the mini file system
and having to run pwd_mkdb to generate the latter)
