Make sure the scheduling class of idle_thread is PRI_IDLE.

Tested by:	semprix[at]rootdrive.org
--- src/sys/kern/kern_idle.c.orig	Wed Jan 26 22:28:21 2005
+++ src/sys/kern/kern_idle.c	Wed Jan 26 22:26:08 2005
@@ -83,7 +83,9 @@
 		td = FIRST_THREAD_IN_PROC(p);
 		TD_SET_CAN_RUN(td);
 		td->td_flags |= TDF_IDLETD;
-		td->td_priority = PRI_MAX_IDLE;
+		sched_class(td->td_ksegrp, PRI_IDLE);
+		td->td_ksegrp->kg_user_pri = PRI_MAX_IDLE;
+		sched_prio(td, PRI_MAX_IDLE);
 		mtx_unlock_spin(&sched_lock);
 		PROC_UNLOCK(p);
 #ifdef SMP