[clang] [Clang] Support using boolean vectors in ternary operators (PR #154145)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

> > errors, but I think to fold it directly we'd need a dedicated builtin. But I'm not a master of the clang AST.
> 
> We shouldn't need a builtin, we should just be able to handle the AST nodes directly in ExprConstant.cpp.

Ah, right. That doesn't work, but it seems like the normal handling doesn't work there either so I'll punt fixing this for another PR https://godbolt.org/z/rTx5n7fao.

https://github.com/llvm/llvm-project/pull/154145