bsd: init netbsd & openbsd userland

Adds a couple of useful NetBSD and OpenBSD derivations. Some of these
will be integrated into Nixpkgs later.

Noncomprehensive list:

- netbsd.getent
- netbsd.getconf
- netbsd.fts
- openbsd.mg
- netbsd.compat (can replace libbsd)

pkgs/build-support/fetchcvs/builder.sh

@@ -1,7 +1,6 @@
 source $stdenv/setup
 
 (echo '#!/usr/bin/env sh'; \
- echo 'echo $@'; \
  echo 'ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no "$@"') > ssh
 chmod +x ssh
 export CVS_RSH=$PWD/ssh