hostnet: transform socket errors into a FLOW.Eof
hostnet: transform socket errors into a FLOW.Eof

If read or write fail, we need to treat these conditions as Eof rather
than fail the thread.

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

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