kernel.passthru: Don't include meta to be consistent with stdenv.mkDerivation

Signed-off-by: Shea Levy <shea@shealevy.com>
===== RG: r/zfstools =====
zfstools: Add new package

zfstools is an OpenSolaris-like and compatible auto snapshotting script
for ZFS, which also supports auto snapshotting mysql databases.
===== RG: r/zfs-import =====
zfs: Fix libblkid detection (backport from upstream)

This fixes issues with importing ZFS pools, such as when the ZFS device is a
partition that covers the end of the disk.

See: https://github.com/zfsonlinux/zfs/issues/1684
zfs: Don't look for devices only in /dev

If we don't give out a directory to 'zpool import', it will use libblkid
to automatically find all existing ZFS devices.
===== RG: r/zfs-autosnap =====
nixos: Add ZFS auto-snapshotting module