[libcxx] [llvm] [libc++] Add tools for gathering historical benchmark data (PR #212775)

[Nikolas Klauser via llvm-commits]

https://github.com/philnik777 commented:

I didn't go through everything in extreme detail, but the overall thing looks good. I'd like to move duplicated utilities into a separate file though if that's not too much work.

https://github.com/llvm/llvm-project/pull/212775