client should compile without warnings on linux, mac, windows

client/util.h

@@ -16,8 +16,12 @@
 #include <ctype.h>
 #include <time.h>
 
-#define MIN(a, b) (((a) < (b)) ? (a) : (b))
-#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+#ifndef MIN
+# define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
+#ifndef MAX
+# define MAX(a, b) (((a) > (b)) ? (a) : (b))
+#endif
 
 int ukbhit(void);