particular, acl support is no longer enabled on FreeBSD 4, acl support
should be correctly enabled on Linux, dirent.d_namlen should be
correctly detected on platforms that support it.
Thanks to: Greg Lewis, Juergen Lock, and Jaakko Heinonen
systems. The fts.h here is an exact copy of include/fts.h (except for
an initial explanatory comment and the revision tags, of course). The
fts.c here is slightly modified from lib/libc/gen/fts.c so it can
compile correctly on non-FreeBSD systems.