bug#43228: r-v8 doesn't build since node 10.22 update

[Mark H Weaver <mhw@netris.org>]

Hi Pierre,

Your new patch looks good to me, but the node-10.22 source field could
be simplified to avoid repeating the unchanged field (especially the
snippet), by inheriting from (package-source node) like this:

--8<---------------cut here---------------start------------->8---
    (source (origin
              (inherit (package-source node))
              (uri (string-append "https://nodejs.org/dist/v" version
                                  "/node-v" version ".tar.xz"))
              (sha256
               (base32
                "1nz18fa550li10r0kzsm28c2rvvq61nq8bqdygip0rmvbi2paxg0"))))
--8<---------------cut here---------------end--------------->8---

Also, it would be great to find a way to fit in the subject line that
10.22 is also being kept as a separate binding, especially since "guix
build node" and most other user commands will still build 10.22.  Maybe
something like this:

  gnu: node: Downgrade to 10.20.0; add separate 'node-10.22' binding.

What do you think?

Anyway, feel free to push this, preferably after incorporating these
suggestions.  If I'm not mistaken, the simplification suggested above
should not change the .drv file, and therefore not entail a rebuild, so
testing it should be very quick.

     Thanks!
       Mark