CACHEPOT_BASEDIR

[montekki]

No description provided.

[montekki]

@drahnr, marking this ready for review.

Just strip CARGO_MANIFEST_DIR from the paths, dont cache the cwd and call it a day. The testing i've done shows that it improves the cache hit rate somewhat but quite honestly I do not think that the task at hand is doable cleanly and safely for all usecases at this point.

Testing done: build cachepot with cachepot.

There still are a lot of absulute paths that end up in the build artifacts such as

1. paths in *.d files.
2. paths in artifacts from the cc builds
3. paths in things that are still built locally such as cdylib crates.

[drahnr]

A rebase and this should be good to go :)

[drahnr]

rustfmt seems unhappy, I'd like to land this soon™ :)