[llvm] [DFAJumpThreading] Rewrite the way paths are enumerated (PR #96127)

[Mikael Holmén via llvm-commits]

mikaelholmen wrote:

I've seen another crash with this patch: ```opt -passes=dfa-jump-threading bbi-98705.ll -o /dev/null```
Results in:
```
opt: ../lib/Transforms/Scalar/DFAJumpThreading.cpp:332: void (anonymous namespace)::unfold(llvm::DomTreeUpdater *, llvm::LoopInfo *, (anonymous namespace)::SelectInstToUnfold, std::vector<SelectInstToUnfold> *, std::vector<BasicBlock *> *): Assertion `SI->use_empty() && "Select must be dead now"' failed.
```
@UsmanNadeem : how is debugging of these crashes (also mentioned in https://github.com/llvm/llvm-project/issues/106083) going?

[bbi-98705.ll.gz](https://github.com/user-attachments/files/16838266/bbi-98705.ll.gz)


https://github.com/llvm/llvm-project/pull/96127