[llvm] [MachineCopyPropagation] Recognise and delete no-op moves produced after forwarded uses (PR #129889)

[David Green via llvm-commits]

davemgreen wrote:

Hi - Can you make a bug-report with what is going wrong and the best (hopefully smallest?!?) reproducer that you have that shows the problem. It might be another orthogonal issue, that is just now surfaced due to this change.

https://github.com/llvm/llvm-project/pull/129889