[Bio-packaging] Ruby gems/bundler support

[Pjotr Prins]

Success! I just compiled the Nokogiri gem with native extensions through both
gem and bundler. See

  https://github.com/pjotrp/guix-notes/blob/master/RUBYGEMS-Nokogiri.org#nokogiri

This covers almost all my Ruby needs. Nokogiri and cucumber both run
fine. Next step, a proper guix package.

Pj.

> > Nokogiri fails because it needs some system include files and
> > libraries. A cleaner native extension will probably compile with the
> > standard build tools.
> 
> Just include libxml2, libxslt, etc. in the build environment of the package.