Added min() and max() functions.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@4173 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/disk_device_manager/KDiskDeviceUtils.h

@@ -13,6 +13,28 @@ namespace DiskDevice {
 
 // helper functions
 
+// min
+template<typename T>
+static inline
+const T&
+min(const T &a, const T &b)
+{
+	if (a < b)
+		return a;
+	return b;
+}
+
+// max
+template<typename T>
+static inline
+const T&
+max(const T &a, const T &b)
+{
+	if (a < b)
+		return b;
+	return a;
+}
+
 // set_string
 static inline
 status_t