Revert "[libc][NFC][Obvious] Fix the benchmarks after the switch to llvm/third-party"

This reverts commit 39e9f5d3685f3cfca0df072928ad96d973704dff.

Reverting, as we needed to re-revert the benchmarks move because it was
causing a build failure in the Fuchsia bots due to the way they consume
libcxx's CMakeLists. I want to make sure I understand where the fix
should be for that. After that, I'll incorporate the change here in the

GitOrigin-RevId: 67de95b8c9556a1c2e715a0b1d4cec709f37055f
1 file changed