ioreg: Resolve shadowed lifetime variables
Fallout from rust #19448

String concantenation is now a bit more painful. Perhaps there's a
better way?

https://github.com/rust-lang/rust/commit/0669a432a2e09ad08886cb2138dbe9f5d681fb7f
SlicePrelude is now SliceExt
platformtree: Fix shadowed lifetime variable
platformtree: Add missing Copy impl