Reintroduce libutil.h #include for FreeBSD only for fparseln

Remove libutil.h #include on FreeBSD and instead favor stdio.h from libnetbsd

Mechanically replace #if defined(__FreeBSD__) and #if defined(__NetBSD__) with
their #ifdef equivalents for everything changed in contrib/netbsd-tests. There
are some items from the vendor tree that use #if defined(__FreeBSD__) or
#if defined(__NetBSD__) which are being left alone

Requested by: bde, rpaulo
Sponsored by: EMC / Isilon Storage Division

libutil.h is required for fparseln on FreeBSD

Sponsored by: EMC / Isilon Storage Division