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

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

> I think we should modify LoopInterchangeProfitability and avoid to interchange the same pair of loops more than once.

I completely agree with this and that sounds like a bug in the cost-model. 

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