[llvm] Add symbol visibility macros to abi-breaking.h.cmake (PR #110898)

[Julian Nagele via llvm-commits]

juliannagele wrote:

> > We should probably make Compiler.h textual.
> 
> Was that tried, @juliannagele?

I wouldn't know I'm afraid, happy to give it a try if you have a patch.

https://github.com/llvm/llvm-project/pull/110898