Previously, we patched pkg-config .pc files to have the absolute path to
the directory where we unpack a python-build-standalone release. As
discussed in #11028, we can use ${pcfiledir} in a .pc file to indicate
paths relative to the location of the file itself.
This change was implemented in astral-sh/python-build-standalone#507, so
for newer python-build-standalone releases, we don't need to do any
patching. Optimize this case by only modifying the .pc file if an actual
change is needed (which might be helpful down the line with hard links
or something). For older releases, change uv's patch to match what
python-build-standalone now does.
## Summary
We had a bug in our handling of escape sequences that caused us to
duplicate backslashes. If you installed repeatedly, we'd keep doubling
them, leading to an exponential blowup.
Closes#10060.
## 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.