(The build process attempted to copy file a overwriting file b, where a
and b are hard-linked, which results in cp returning a non-zero exit
code.)
https://github.com/NixOS/nixpkgs/issues/4266
Ruby >= 2.1.0 will try to download config.{sub,guess} if not already present.
This provides both files in a pure manner, and also deletes the download script
to prevent any future confusion.
* add the 2.1.x versions
* include teeny version in passthru
* by default, apply the same patches used by RVM
* clean up file names and attribute names
