ecd44958e0
Make `BorrowedFd::borrow_raw` a const fn. Making `BorrowedFd::borrow_raw` a const fn allows it to be used to create a constant `BorrowedFd<'static>` holding constants such as `AT_FDCWD`. This will allow [`rustix::fs::cwd`] to become a const fn. For consistency, make similar changes to `BorrowedHandle::borrow_raw` and `BorrowedSocket::borrow_raw`. [`rustix::fs::cwd`]: https://docs.rs/rustix/latest/rustix/fs/fn.cwd.html r? `@joshtriplett`