libproxy: CloseRead is unnecessary (but CloseWrite is)
libproxy: CloseRead is unnecessary (but CloseWrite is)

In particular `go-winio`'s Pipe does not support `CloseRead` so
previously we couldn't proxy it.

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

djs55/vpnkit,djs55/vpnkit,djs55/vpnkit