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

[Steven Michaud via llvm-commits]

steven-michaud wrote:

As a footnote, I also discovered that `-flto` (and link time optimization) has nothing to do with the copy propagation that this commit is concerned with.


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