[clang] [clang][NFC] Annotate `Type` bit-fields with `clang::preferred_type` (PR #70349)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

That's a good point. I'm not opposed to wrap this attribute if we must. I'd like to hear from @AaronBallman on this matter.

https://github.com/llvm/llvm-project/pull/70349