[llvm] [Passes] Move LoopInterchange into optimization pipeline (PR #145503)

[Ryotaro Kasuga via llvm-commits]

kasuga-fj wrote:

> In light of enabling by default, would be good to check the compile time impact for the new position, which may have less overhead?

I believe it reduces overhead, but I didn't actually measure it. Anyway, I’m planning to work on reducing the compile time of LoopInterchange, so I will take the impact then as well.

https://github.com/llvm/llvm-project/pull/145503