[llvm] [LoopInterchange] Enable it by default (WIP) (PR #124911)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

> Has https://github.com/llvm/llvm-project/issues/116144 (correctness issue) been addressed?

It would have been fixed with #119345 . As far as I know, there are no known correctness issues on the LoopInterchange side.

https://github.com/llvm/llvm-project/pull/124911