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

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

Thanks for your thoughts on this. I will go ahead and remove the cl::opt option. If I am not mistaken, I don't see precedent for having both the clang and cl::opt option, and for the use of opt I don't think we'll need the -enable-loopinterchange option. 

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