ikev1: Avoid fourth QM message if third QM messages of multiple exchanges are handled delayed

If we haven't received the third QM message for multiple exchanges the
return value of NEED_MORE for passive tasks that are not responsible for
a specific exchange would trigger a fourth empty QM message.

Fixes: 4de361d92c ("ikev1: Fix handling of overlapping Quick Mode exchanges")

References #1076.

src/libcharon/sa/ikev1/tasks/quick_mode.c

@@ -1026,7 +1026,7 @@ METHOD(task_t, process_r, status_t,
 {
 	if (this->mid && this->mid != message->get_message_id(message))
 	{	/* not responsible for this quick mode exchange */
-		return NEED_MORE;
+		return INVALID_ARG;
 	}
 
 	switch (this->state)
@@ -1200,7 +1200,7 @@ METHOD(task_t, build_r, status_t,
 {
 	if (this->mid && this->mid != message->get_message_id(message))
 	{	/* not responsible for this quick mode exchange */
-		return NEED_MORE;
+		return INVALID_ARG;
 	}
 
 	switch (this->state)