[clang] [Clang] Actually fix tests for __builtin_vectorelements (PR #69589)

[Lawrence Benson via cfe-commits]

lawben wrote:

@nikic Could you please double-check if the syntax here is correct. After the mistake in #69582, I'm a bit nervous about merging a wrong fix again... 😅 

https://github.com/llvm/llvm-project/pull/69589