* breakpoint.c (bpstat_stop_status): Add new argument

	STOPPED_BY_WATCHPOINT.  Use it instead of testing
	target_stopped_data_address agaist 0 to check whether
	or not we stopped due to a hardware watchpoint.
	* breakpoint.h (bpstat_stop_status): Adapt prototype.
	* infrun.c (handle_inferior_event): Call bpstat_stop_status
	with new argument.