Include source archives for jruby and truffleruby? about ruby-versions

[eregon]

This seems to be already the case for JRuby, as @havenwood added them.
The ./update.sh script in this repo doesn't add them though.

Is there a use-case for checksums of the source archives of truffleruby?

Note that it's not supported and not tested to build truffleruby from the source archives automatically created by GitHub on the tags (such as https://github.com/oracle/truffleruby/archive/vm-1.0.0-rc5.tar.gz), as building needs a few external dependencies like a JDK with JVMCI and the Graal VM suite, etc. Instead, releases are created by building the Graal VM suite.

[postmodern]

Mainly to future-proof the repository. ruby-versions can/could be used for other things other than building from source.

[eregon]

OK, no objections then. I like that my PRs to update TruffleRuby touch just two lines per file (e.g. 786ed34) but that's not really important.

One interesting fact is that the link above actually downloads an archive named truffleruby-vm-1.0.0-rc5.tar.gz (and not vm-1.0.0-rc5.tar.gz). Not sure how should ruby-versions deal with that.

[postmodern]

I''m guessing changing exts=(...) to be files=(...) so it's more flexible.