[clang] Clang tooling generated visibility macros for Clang (PR #109702)

[Reid Kleckner via cfe-commits]

rnk wrote:

> Is there a plan for maintaining these annotations long-term? Like, should there be a pre-commit action to verify that all the annotations are up-to-date?

pre-commit actions are expensive, but I think we could afford to do something here. It is not hard to set up a DLL build of an ELF DSO build that uses these annotations, and it's cheaper than a fully static build.

https://github.com/llvm/llvm-project/pull/109702