[llvm] Reapply "[llvm][lit] Add option to run only the failed tests" (PR #171588)

[James Henderson via llvm-commits]

https://github.com/jh7370 commented:

Basically looks good, but I think the fix needs calling out in a comment in the code, because it's not obvious at all.

Also, the PR description needs amending to include the original PR description, so that people don't have to go link hopping to find the original description.

https://github.com/llvm/llvm-project/pull/171588