When wakeup(9) is going to notify swapper, assert that wait channel is not

equal to &proc0. It shall be not, since proc0 stack is not swappable, and
kick_proc0() is wakeup(&proc0).

Reviewed by:	jhb
Approved by:	re (kensmith)

sys/kern/kern_synch.c

@@ -347,8 +347,11 @@ wakeup(void *ident)
 	sleepq_lock(ident);
 	wakeup_swapper = sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0);
 	sleepq_release(ident);
-	if (wakeup_swapper)
+	if (wakeup_swapper) {
+		KASSERT(ident != &proc0,
+		    ("wakeup and wakeup_swapper and proc0"));
 		kick_proc0();
+	}
 }
 
 /*