Networked X11 clients have the annoying property that they need to
contact the X server.  Since most of the useful cases these days
are local, add a toggle which forwards PF_LOCAL sockets to the host
and all other protocol families to the rump kernel.

This makes an unmodified firefox work with a rump TCP/IP stack.
I'm sure someone will find applications for being able to run
multiple web browser profiles on one OS with each browser having
a different IP address in the same subnet ...

(pooka)