[llvm] [LoopInterchange] Don't consider loops with BTC=0 (PR #167113)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

> This is rebased/merged. The changes here to pr43326.ll and pr57148.ll should indeed have been included in #167748, but I missed them earlier. They were a bit masked by other things, and I discovered them during the rebase/changes here.

Ah, I see, I misunderstood.

https://github.com/llvm/llvm-project/pull/167113