Hopefully this won't break anybody: while all tests still pass, there
could in theory be systems where not supplying those libraries leads to
linker errors.
This allows us to test and use LLVM 17, now that it is available in
Homebrew.
Full support for LLVM 17 (including using it by default) will have to
wait until Espressif rebases their Xtensa fork of LLVM.