com.docker.slirp: pass in listening sockets for port forward control
com.docker.slirp: pass in listening sockets for port forward control

The com.docker.osx.xhyve.linux process binds the sockets before starting
any processes and then passes them to com.docker.slirp, which then runs
9P servers on the accepted connections.

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

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