com.docker.slirp: delete the ability to listen on a Unix domain socket
com.docker.slirp: delete the ability to listen on a Unix domain socket

This was previously needed to connect to the docker socket and diagnostics
server, but now that we have vsock we can delete it.

Signed-off-by: David Scott <63c9eb0ea83039690fefa11afe17873ba8278a56@docker.com>

djs55/vpnkit,samoht/vpnkit,djs55/vpnkit,djs55/vpnkit