Change scope of propagate_event for use in io_mac.m

-propagate_event was static in events.c
-io_mac.m uses propagate_event when receiving data before finishing the handshake

src/events.h

@@ -54,6 +54,8 @@ void wiiuse_pressed_buttons(struct wiimote_t* wm, byte* msg);
 
 void handshake_expansion(struct wiimote_t* wm, byte* data, uint16_t len);
 void disable_expansion(struct wiimote_t* wm);
+
+void propagate_event(struct wiimote_t* wm, byte event, byte* msg);
 /** @} */
 
 #endif /* EVENTS_H_INCLUDED */