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

[Steven Michaud via llvm-commits]

steven-michaud wrote:

I've submitted two `lldb` session transcripts [here](https://github.com/llvm/llvm-project/issues/166870): a "good" one and a "bad" one.


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