bsd-user: Remove bsd_type

bsd-user: Remove bsd_type

Remove keeping track of which type of bsd we're running on. It's no
longer referenced in the code. Building bsd-user on NetBSD or OpenBSD
isn't possible, let alone running that code. Stop pretending that we can
do the cross BSD thing since there's been a large divergence since 2000
that makes this nearly impossible between FreeBSD and {Net,Open}BSD and
at least quite difficult between NetBSD and OpenBSD.

Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Kyle Evans <kevans@FreeBSD.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>