[clang] [coroutines] proposal for regresssion tests

I think it makes sense to separate this from #241761

Proposal: add kelcoro and its full test suite to llvm-test-suite

Every clang release since 14 to 23 has failed on kelcorowith different coroutines related ICE/error

kelcoro is small enough to build and run on every release candidate, so regressions like this one would be caught in rc1 instead of in user code

@llvm/issue-subscribers-coroutines

Author: kelbon

Details

I think it makes sense to separate this from #241761

Every clang release since 14 to 23 has failed on kelcorowith different coroutines related ICE/error

kelcoro is small enough to build and run on every release candidate, so regressions like this one would be caught in rc1 instead of in user code