d92c43bd21
Use of grep in `lit` RUN lines is deprecated:
https://llvm.org/docs/TestingGuide.html#writing-new-regression-tests
Using grep leads to really unhelpful failure output (it literally
just says "the test failed"). FileCheck is much more helpful, and
distributed with LLVM on most distros anyway, so this extra
dependency shouldn't prove problematic.
[ROCm/clr commit: 3868036ea7]