## Summary
This PR reimplements
[`sysconfigpatcher`](https://github.com/bluss/sysconfigpatcher) in Rust
and applies it to our Python installations at install-time, ensuring
that the `sysconfig` data is more likely to be correct.
For now, we only rewrite prefixes (i.e., any path that starts with
`/install` gets rewritten to the correct absolute path for the current
machine).
Unlike `sysconfigpatcher`, this PR does not yet do any of the following:
- Patch `pkginfo` files.
- Change `clang` references to `cc`.
A few things that we should do as follow-ups, in my opinion:
1. Rewrite
[`AR`](c1ebf8ab92/src/sysconfigpatcher.py (L61)).
2. Remove `-isysroot`, which we already do for newer builds.
