mask out any action when copying the flags from the event to the knote..

Pointed out by:	Václav Haisman
Submitted by:	Dan Nelson (slightly modifed patch)
MFC after:	3 days

sys/kern/kern_event.c

@@ -887,6 +887,8 @@ kqueue_register(struct kqueue *kq, struct kevent *kev, struct thread *td, int wa
 			kev->fflags = 0;
 			kev->data = 0;
 			kn->kn_kevent = *kev;
+			kn->kn_kevent.flags &= ~(EV_ADD | EV_DELETE |
+			    EV_ENABLE | EV_DISABLE);
 			kn->kn_status = KN_INFLUX|KN_DETACHED;
 
 			error = knote_attach(kn, kq);