Upgrade llvm-project (rustc + avr = lovelove back again!)
See:
https://github.com/rust-lang/llvm-project/pull/139
tl;dr:
- closes https://github.com/rust-lang/rust/issues/83633,
- closes https://github.com/rust-lang/rust/issues/82104,
- closes https://github.com/rust-lang/rust/issues/79889,
- closes https://github.com/rust-lang/compiler-builtins/issues/400.
🙂