net: add stubs for NetBSD
net: add stubs for NetBSD

This fixes the build of package net for GOOS=NetBSD.
Of course, a real implementation would be even better.

R=golang-dev, r
CC=golang-dev
http://codereview.appspot.com/5693065

Committer: Rob Pike <4dc7c9ec434ed06502767136789763ec11d2c4b7@golang.org>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang