[llvm] [DebugInfo][JumpThreading] Fix missing debug location updates (PR #91581)

[Orlando Cazalet-Hyams via llvm-commits]

https://github.com/OCHyams commented:

Thanks for another helpful fix! Code changes LGTM but I've got a couple of questions about the tests in-line.

https://github.com/llvm/llvm-project/pull/91581