Handle compatible libc-based manylinux/musllinux platform tags

[q0w]

Closes #10760

[pradyunsg]

Thanks for filing this! I have two major blocking concerns with this PR:

1. The news fragment isn't sufficiently clear about the fact that this only affects cases when certain flags are passed. Further, it'd be nice to use :pep: inline role to reference PEPs or, even better, use a textual description of what the PEP represents in the news fragment.
2. The implementation uses a private function from packaging.tags, which I don't like the idea of doing.

[pradyunsg]

@q0w I appreciate the work you're putting toward this but could you clarify what implementation approach you're taking here? It looks like you've basically copied over code from packaging.tags after I mentioned that it's a no-go to use packaging.tag's internals -- both are equally bad and I'm not sure how you're expecting this PR to behave.

[uranusjr]

Logic looks right to me, although the news fragment definitely needs to better describe what users should expect from this change. Also the implementation can be slightly improved, I think.

[pradyunsg]

An alternative to this is to go the route of requiring users to specify the entire environment: #10050 (comment)

[ofek]

Is there anything blocking this from being merged?

[uranusjr]

Personally I think this needs some better text explaining the scope of the feature, likely somewhere in documentation.

[q0w]

I am not good at writing docs, so if someone wants to collaborate, ping me