Instead of injecting an empty resolv.conf with an includes.chroot, we'll
inject it in late with a hook. The empty resolv.conf breaks DNS early in
the build, and causes some binary hooks to fail.
Installing policyrcd-script-zg2 doesn't quite do this because of the way
that live-build installs its own temporary version of policy-rc.d. The
only remotely sensible way I can see to deal with this is to create the
symlink manually.
