Running optimizeTerminators prior to other optimizations like branch
layout can lead to more folding and better codegen, but is not on its
own able to capture all cases. There is benefit to running it in both
places. This adds the existing code from #161508 into the
AArch64RedundantCopyElimination pass, which sounds like a sensible
enough place for it.
This is a recommit with an extra fix for shrink-wrapping domtree use.
8a4cc440f2