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

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

https://sourcegraph.com/search?q=context:global+__builtin_shufflevector%5C%28%5BA-Za-z0-9_%5D%2B%2C.%5BA-Za-z0-9_%5D%2B%5C%29+-file:.*test.*&patternType=regexp&case=yes&sm=0 doesn't show use in the wild, but perhaps someone can devise a better search string. In the meantime, I'm more comfortable limiting the changes to rejecting use in a constant expression.

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