[llvm] [LoopInterchange] Relax the legality check to accept more patterns (PR #118267)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

@Meinersbur Hi, let me ask a question. Should I bring this kind of topic to the LoopOpt WG meeting? This is because, looking at past discussion logs, it seems that the correctness of the legality check has often been discussed on the LoopWG call. Or is a text discussion on GitHub sufficient?

https://github.com/llvm/llvm-project/pull/118267