Darwin and FreeBSD are compatible enough to share the userspace router.
The OSX router delegates to the BSD userspace router unless `SetRoutesFunc` is set.
That preserves the mechanism that allows `ipn-go-bridge` to specify its own routing behavior.
Fixes#177
Signed-off-by: Reinaldo de Souza <github@rei.nal.do>
Instead, pass in only exactly the relevant configuration pieces
that the OS network stack cares about.
Signed-off-by: David Anderson <danderson@tailscale.com>
