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

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

I have no idea how much the two-argument version of __builtin_shufflevector is used in practice.  I wouldn't want to remove it without a better idea of that... I vaguely recall it might be relevant for some GPU languages.

It should be possible to fix the crash by just rejecting it from constant evaluation.

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