[openbsd-compat/port-tun.c openbsd-compat/port-tun.h] Add support
for tunnel forwarding for FreeBSD and NetBSD. NetBSD's support is
limited to IPv4 tunnels only, and most versions don't support the
tap(4) device at all.
[serverloop.c ssh.c openbsd-compat/Makefile.in]
[openbsd-compat/openbsd-compat.h] Implement tun(4) forwarding
compatability support for Linux, diff from reyk@