Hi Guix!

This small series adds camlboot, a project to reimplement a bootstrap
for OCaml, which lets us remove the pre-built boot/ocaml{c,lex} :)

The first patch builds the bootstraped ocamlc and ocamllex. This takes
around 4 hours to build. The second patch rebuilds them using the source
code for ocaml 4.07.1, instead of the modified sources used in
camlboot, and reuse them to run the main Makefile (make world.opt).

As a result, we have identical files for this bootstrap and the
unbootstrapped OCaml (up to output store paths and hash of some files
that get embedded in native files, which differ because of the
different output path).