tap-vsockd: support reconnection
tap-vsockd: support reconnection

If the server side crashes and is restarted, this patch makes
tap-vsockd reconnect so the network is restored.

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

djs55/vpnkit,djs55/vpnkit,djs55/vpnkit