Provide an easy way to not ruin the target rootfs when doing the copy to target actions

[bradfa]

Normally, at the end of the book, around when we do copy to target, we tell people to delete all the static libs, headers, and unneeded .so links. This is fine but it means that we can't continue to build for the targetfs any more as we kind of need those things in order to compile code.

So maybe add an intermediate step or otherwise provide a way to not delete these things but to still create the tarball without them.