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

[David Sherwood via llvm-commits]

david-arm wrote:

> This sounds very similar to #168709. Does the crash still crash on latest `main`

I think I'm using quite a recent version of 'main' that's only a couple of days old.

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