[llvm] [BOLT] Fix archive output directory for standalone on Mac (PR #100643)

[via llvm-commits]

gulfemsavrun wrote:

> CC @gulfemsavrun
> 
> Fixes a line which wasn't changed in #97130

Thanks, this fixed the problem I reported in https://github.com/llvm/llvm-project/pull/97130#issuecomment-2251251721!

https://github.com/llvm/llvm-project/pull/100643