[clang] [Clang][FIX] Fix type qualifiers on vector builtins (PR #160185)

[John McCall via cfe-commits]

https://github.com/rjmccall commented:

Thanks, that's definitely a significant step closer. I've given this a more detailed review. Unfortunately, writing builtins with custom type-checking can be a little tricky because of the range of languages we support in Clang. It mostly just involves making calls that you're supposed to be making anyway and checking for dependent types, but it's something every builtin needs to be doing.

https://github.com/llvm/llvm-project/pull/160185