Getting to rust-1.62:

- Must build rust versions in order: 1.58 -> 1.59 -> etc.

- Big hurdle:  Rust 1.60 and up needs llvm-14 (not llvm-13).  This is hard to do, because previous version of rust will want llvm-13, and you can't have 13 + 14 installed at the same time.


Solution:

1.61: build with llvm-14.0.0-1, but clang-13 and lld-13.  This works because llvm-14.0.0-1 (first llvm-14) provides llvm-13, Allowing us to use clang + lld 13.
(llvm-14.0.0-1 is a "transition package", provides both major llvm library versions)

1.62: build with full latest llvm + clang + lld 14, as previous rust-1.61 should now only rely on llvm 14.