[libcxx] [libcxxabi] [libunwind] [llvm] [libc++] Unify the benchmarks with the test suite (PR #101399)

[Louis Dionne via cfe-commits]

ldionne wrote:

> I do care. I sometimes like to compare benchmarks from different iterations. Currently when I build a benchmark I get a message where the executable is stored. The new approach makes harder to find the location of the executable. I wonder whether we can show a message where the benchmark is stored, maybe always print the location in `format.py`?

If you run the test suite verbosely (I like to use Lit's `--show-all` option), it shows where the executables are created. That way you can copy the executable to the location of your choosing. What's nice is that we now handle benchmarks consistently with all other tests, so this process also applies to any test executable you might want to copy around.

https://github.com/llvm/llvm-project/pull/101399