[llvm] [mlir] [mlir][OpenMP] Fix taskloop outlined step handling (PR #190198)

[Tom Eccles via llvm-commits]

tblah wrote:

I haven't run the fujitsu test sutie on this because I am running out of memory trying to build them even on main. I will investigate if the issue persists.

@Stylie777 my worry with this PR is COLLAPSE(). Does the cannonical loop normalise the step value in a way that makes reloading it incorrect?

https://github.com/llvm/llvm-project/pull/190198