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

[Michael Buch via llvm-commits]

Michael137 wrote:

> 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.

Added a comment and copied the description from the original PR (though it was quite brief).

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