[llvm] [LoopInterchange] Fix overflow in cost calculation (PR #111807)

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

> Is it possible to test this more targeted via an analysis test in `llvm/test/Analysis/LoopCacheAnalysis/`?

Thanks for the suggestion, that worked, have moved it.

https://github.com/llvm/llvm-project/pull/111807