drbbdup fails to restore state for its register spills

I'm hitting another issue with drbbdup when we try to use it by default for drmemtrace #2039: drbbdup spills one or two registers and possibly the flags for its dispatch logic, using custom spills (because its control flow doesn't mesh well with drreg). But it doesn't have a restore state event. So a detach or other asynch translation event will mess up the app register state. We are seeing crashes post-detach that we suspect are coming from this.