[Toybox] FreeBSD support.

[Rob Landley]

Ed Maste did https://github.com/landley/toybox/pull/113 and I (more or less)
applied 4 of his changes. The 5th is expecting /usr/bin/env to be at an absolute
path but not /bin/bash, which... how is one more trustworthy than the other? The
extra layer of indirection buys what? (Python isn't a _real_ part of the system,
we can't allow unwashed foreign commands to install into /usr/bin, they have to
go in /opt/local/maybe/dmz/bin...)

Other than that, Ed says:

> With this change I can build these posix toys:
>
> % ./toybox
> basename cal cat catv chgrp chmod chown cksum cmp comm cpio crc32
> cut date dirname du egrep expand false fgrep file find grep groups
> head iconv id kill killall5 link logger logname ls mkdir mkfifo nice
> nl nohup od paste patch printf pwd renice rm rmdir sed sleep sort
> split strings tee test time touch true tty uname uniq unlink uudecode
> uuencode wc who whoami xargs
>
> Notable missing POSIX toys:
> cp mv install df getconf ln ps top iotop pgrep pkill tail

Which sounds a bit like where MacOS left off. I think I need some sort of "make
macos_defconfig" and "make freebsd_defconfig" targets pulling in relevant
default configurations. (Which should be separate files rather than trying to
annotate every command with which targets can build it; that way lies madness,
as gentoo discovered)...

Rob

P.S. I should get a FreeBSD vm set up with a build environment. I couldn't do it
for MacOS because their stupid "check the fan controller for an install key
because piracy piracy piracy even if you bought a BOXED copy of MacOS" and after
https://lists.gnu.org/archive/html/qemu-devel/2008-02/msg00443.html I just went
"Apple is too dumb to live" and ignored them (and as far as I could tell, Darwin
died almost immeidately, ala http://landley.net/notes-2007.html#28-11-2007 ),
but I've _almost_ got working BSD versions on more than one occasion. (With help
from Randi Harper and Kirk McKusick over the years, and it still didn't _quite_
work, but I can try again...)