Here is a patch to make hardware watchpoints work in precord.

Biggest change is in breakpoint.c, but it's mainly mechanical.
I abstracted most of the function "watchpoint_check" into a
separate function so it could be called from two places.

Then in record_wait, if not replay mode we call
target_stopped_by_watchpoint to see if a watchpoint
was triggered.  In replay mode we call the new function
hw_watchpoint_check.