pkg/libproxy: add simulated latency to loopbackconn
pkg/libproxy: add simulated latency to loopbackconn

This will make it easier to trigger certain race conditions.

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

djs55/vpnkit,djs55/vpnkit,djs55/vpnkit