[llvm] LoopVectorize: add test for crash #47665 (PR #91135)

[Florian Hahn via llvm-commits]

fhahn wrote:

Could you also add the test case from https://github.com/llvm/llvm-project/issues/88802? 

For the title, I'd recommend using `[LV]` which is much more compact and leaves more room for more descriptive titles

https://github.com/llvm/llvm-project/pull/91135