One final pass in opte-drv (#214)

- Did a final sweep in opte-drv to see if there was anything else to
  migrate over to xde.

- Moved over the _Unwind_Resume hack. It seems xde has been working
  fine without it, but I also notice the Rust issue that originally
  prompted me to create this hack is still marked as open. So I
  thought it would be best to migrate the hack over to xde just as a
  safeguard against the problem coming back until that Rust issue is
  resolved.

  rust-lang/rust#47493