Use asdf to get a "portable" setup for a large set of implementations

[smarr]

I am currently starting to use asdf to setup my own benchmarking infrastructure. This seems a comprehensive enough project to support a broad range of the language implementations we may want to compare.

@eregon any thoughts? It seems fine from what I have seen so far, but perhaps you know about rough edges?

[eregon]

asdf uses ruby-build for ruby and ruby-build is the best Ruby installer, so no concerns from my side. One thing is asdf like rbenv uses shims which means a small overhead when starting a process (but very likely doesn't matter for these benchmarks as we don't time the whole process) and might need to rehash manually every now and then.

I have read recently that rbenv can have a non-trivial cost on shell-startup, but I'm not sure if still the case and whether it affects asdf too. (doesn't matter for these benchmarks)

[smarr]

Ok, great, thanks.

At the moment, I have not really "installed" asdf, and actually just use it as a downloader with a consistent set of commands, so, even if we'd be interested in startup cost, I am using direct path to the executables.

[eregon]

Even better then!