This directory had example scripts for util-linux's getopt. They count
as documentation and don't belong on an embedded rootfs.
This also reduces the diff to RescueOS v1.1; this directory was
(presumably manually) removed there as well.
Also cleanup post-build.sh a bit while we're at it.
Setup buildroot filesystem overlay and move our custom scripts/configs
into it. Setup a post-build script and have it delete files generated
by buildroot that aren't in RescueOS v1.1.
This gets us closer to a buildroot configuration that will automatically
generate RescueOS images. For now, we're using RescueOS v1.1 as a
reference.
