Rollup of 7 pull requests
Successful merges:
- #123530 (Enable building tier2 target riscv32im-unknown-none-elf)
- #123642 (do not allow using local llvm while using rustc from ci)
- #123716 (Update documentation of Path::to_path_buf and Path::ancestors)
- #123876 (Update backtrace submodule)
- #123888 (Replace a `DefiningOpaqueTypes::No` with `Yes` by asserting that one side of the comparison is a type variable.)
- #123890 (removed (mostly) unused code)
- #123891 (Miri subtree update)
r? `@ghost`
`@rustbot` modify labels: rollup
618c300497