Small BlinkM fix

Marlin/BlinkM.cpp

@@ -2,6 +2,7 @@
   BlinkM.cpp - Library for controlling a BlinkM over i2c
   Created by Tim Koster, August 21 2013.
 */
+#include "Marlin.h"
 #ifdef BLINKM
 
 #if (ARDUINO >= 100)