Conditional definition of MIN/MAX macros.

prrt/defines.h

 #ifndef PRRT_DEFINES_H
 #define PRRT_DEFINES_H
 
+#ifndef MAX
 #define MAX(x, y) (((x) > (y)) ? (x) : (y))
+#endif
+
+#ifndef MIN
 #define MIN(x, y) (((x) < (y)) ? (x) : (y))
+#endif
 
 #define PRRT_MAX_RECEIVER_COUNT 255