[llvm] LoopVectorize: add test for crash in #72969 (PR #74111)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

Hi @david-arm,

Sorry I'm behind on my PRs: I'm currently on vacation, due to return to work in mid-March.

As for this PR, since the test is fine, I think we can merge it as-is, to document the failure. I'll try to pick up #74456 soon and complete it. What do you think?

https://github.com/llvm/llvm-project/pull/74111