[libclc] [libcxx] [llvm] [openmp] [polly] [llvm] Move sub-project lead maintainers into their own Maintainers.md files (PR #118309)

[Fraser Cormack via cfe-commits]

frasercrmck wrote:


> For libclc maybe @tstellar -> @frasercrmck (or maybe both).

I'm not opposed to this if people think it suitable. But having someone from Red Hat or AMD as co-maintainer(s) makes sense to me, as it's a project used (downstream) by several different groups.

https://github.com/llvm/llvm-project/pull/118309