[clang] disable unary, vector mask (PR #130400)

[Timm Baeder via cfe-commits]

tbaederr wrote:

It sounds a little weird to allow the vector+int version only in codegen and not in constant evaluation. If we reject it, we should do that in Sema I think.

git blame for `Sema::BuiltinShuffleVector` is all over the place, so pinging @AaronBallman @cor3ntin to see if this goes in the right direction.

https://github.com/llvm/llvm-project/pull/130400