Add MIN MAX macro to param header file.

newlib/ChangeLog:
2015-07-28  Andre Vieira  <andre.simoesdiasvieira@arm.com>

   * libc/sys/arm/sys/param.h (MIN,MAX): Define.

From 536ca7365d269f5e56679048e336d6969186d550 Mon Sep 17 00:00:00 2001
From: Andre Simoes Dias Vieira <andsim01@arm.com>
Date: Tue, 28 Jul 2015 14:19:08 +0100
Subject: [PATCH] Added min max macros

newlib/libc/sys/arm/sys/param.h

@@ -16,4 +16,7 @@
 # define PATHSIZE (1024)
 #endif
 
+#define MAX(a,b) ((a) > (b) ? (a) : (b))
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+
 #endif