include axoupdater in glibc version computations, somehow

With #1210 we now compute system requirements to install a binary more precisely but we don't factor in axoupdater if they use the (prebuilt) binary version of axoupdater, and there's no reason it should have to be built on the same level of glibc.

This isn't a huge issue since it's a pre-existing imprecision but we should figure this out at some point.

Maybe this involves reading the dist-manifests of the release we fetch axoupdater from?

Start by tracing the system-requirement and glibc computation introduced with #1210, then inspect how the release containing axoupdater is fetched. Review that release's dist-manifests as suggested, and define how a prebuilt axoupdater's glibc requirement should be represented. Done means the computation no longer assumes axoupdater was built at the same glibc level.

Written by the indexing model from the issue text.