exec.c: Record watchpoint fault address and direction

exec.c: Record watchpoint fault address and direction

When we check whether we've hit a watchpoint we know the address
that we were attempting to access and whether it was a read or a
write. Record this information in the CPUWatchpoint struct so that
target-specific code can report it to the guest.

Signed-off-by: Peter Maydell <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>