[clang] [AST] Include clang/Basic/DiagnosticComment.h instead of clang/AST/CommentDiagnostic.h (PR #117499)

[Kazu Hirata via cfe-commits]

kazutakahirata wrote:

I'm going to go conservative for now by including `clang/Basic/DiagnosticComment.h` instead of `clang/AST/CommentDiagnostic.h`.  We can revisit this and remove `clang/AST/CommentDiagnostic.h` and update `module.modulemap`.

https://github.com/llvm/llvm-project/pull/117499