[llvm] IndVarSimplify: fix high-cost-expand check (PR #125828)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Hm, it seems like costing IVLimit instead of ExitCount ends up having the opposite effect and we do more LFTR? Is IVLimit usually a simpler expression than ExitCount?

https://github.com/llvm/llvm-project/pull/125828