* remote.c (struct remote_state) <waiting_for_stop_reply>: New

	* remote.c (struct remote_state) <waiting_for_stop_reply>: New
	field.
	(remote_open_1): Clear waiting_for_stop_reply.
	(remote_resume): Set waiting_for_stop_reply.
	(remote_wait): Clear or set waiting_for_stop_reply accordingly.
	(putpkt_binary): If we're in async mode and waiting for a stop
	reply, bail out with an error.
	(extended_remote_mourn_1): Clear waiting_for_stop_reply.