[llvm] [LV] Fix random behaviour in LoopVectorizationLegality::isUniform (PR #170463)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

This sounds very similar to https://github.com/llvm/llvm-project/issues/168709. Does the crash still crash on latest `main`?

https://github.com/llvm/llvm-project/pull/170463