[polly] [Polly] Do not assume loops to be bounded if latch conditions are invalid (PR #226202)

[Michael Kruse via llvm-commits]

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Meinersbur wrote:

I created a followup for when this case is hit here: #226515

I think the `buildConditionSets` is just called somwehere else.

https://github.com/llvm/llvm-project/pull/226202