$OpenBSD$

Silence warning.

--- hardware/arduino/avr/cores/arduino/Arduino.h.orig	Sat Apr  4 15:51:57 2015
+++ hardware/arduino/avr/cores/arduino/Arduino.h	Sat Apr  4 15:52:52 2015
@@ -120,7 +120,7 @@ typedef uint8_t byte;
 void init(void);
 void initVariant(void);
 
-int atexit(void (*func)()) __attribute__((weak));
+int atexit(void (*func)(void)) __attribute__((weak));
 
 void pinMode(uint8_t, uint8_t);
 void digitalWrite(uint8_t, uint8_t);
