Add a basic (currently failing) sanity check for btrfsProgs-in-initrd

Signed-off-by: Shea Levy <shea@shealevy.com>
Fix btrfs in the initrd.

With NixOS/nixpkgs@7761952d06d3e2c535f00d38796f98228b3946bb , btrfs requires libz and liblzo2

Signed-off-by: Shea Levy <shea@shealevy.com>