don't rely on sys/param.h having a MAX macro.

Switch to local definitions where MAX is needed.
discussed with deraadt@

src/usr.sbin/ntpd/client.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: client.c,v 1.93 2014/05/12 20:50:46 miod Exp $ */
+/*	$OpenBSD: client.c,v 1.94 2015/01/04 01:19:46 bcook Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -121,13 +121,15 @@ client_nextaddr(struct ntp_peer *p)
 	return (0);
 }
 
+#define SCALE_MAX(a, b) ((a) > (b) ? (a) : (b))
+
 int
 client_query(struct ntp_peer *p)
 {
 	int	val;
 
 	if (p->addr == NULL && client_nextaddr(p) == -1) {
-		set_next(p, MAX(SETTIME_TIMEOUT,
+		set_next(p, SCALE_MAX(SETTIME_TIMEOUT,
 		    scale_interval(INTERVAL_QUERY_AGGRESSIVE)));
 		return (0);
 	}
@@ -150,7 +152,7 @@ client_query(struct ntp_peer *p)
 			if (errno == ECONNREFUSED || errno == ENETUNREACH ||
 			    errno == EHOSTUNREACH || errno == EADDRNOTAVAIL) {
 				client_nextaddr(p);
-				set_next(p, MAX(SETTIME_TIMEOUT,
+				set_next(p, SCALE_MAX(SETTIME_TIMEOUT,
 				    scale_interval(INTERVAL_QUERY_AGGRESSIVE)));
 				return (-1);
 			} else

src/usr.sbin/ntpd/ntp.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: ntp.c,v 1.122 2015/01/04 01:16:10 bcook Exp $ */
+/*	$OpenBSD: ntp.c,v 1.123 2015/01/04 01:19:46 bcook Exp $ */
 
 /*
  * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
@@ -734,13 +734,15 @@ update_scale(double offset)
 		conf->scale = QSCALE_OFF_MAX / offset;
 }
 
+#define SCALE_MAX(a, b) ((a) > (b) ? (a) : (b))
+
 time_t
 scale_interval(time_t requested)
 {
 	time_t interval, r;
 
 	interval = requested * conf->scale;
-	r = arc4random_uniform(MAX(5, interval / 10));
+	r = arc4random_uniform(SCALE_MAX(5, interval / 10));
 	return (interval + r);
 }