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

[Louis Dionne via llvm-commits]

ldionne wrote:

@boomanaiden154 This is basically the tooling I was talking about in https://github.com/llvm/llvm-project/pull/212591

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