[llvm] [SimplifyCFG] Avoid calling `paramHasNonNullAttr` on a ptr vector argument (PR #207195)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

LGTM, though I think it would make sense to add support for `nonnull` on vector of pointer arguments.

https://github.com/llvm/llvm-project/pull/207195