Remove Nullptr.h from Arduino.h

The nullptr define should only be used inside unittest functions,
elsewhere it breaks code.

Author: hlovdal

cpp/arduino/Arduino.h

@@ -15,7 +15,6 @@ Where possible, variable names from the Arduino library are used to avoid confli
 #include "Stream.h"
 #include "HardwareSerial.h"
 #include "SPI.h"
-#include "Nullptr.h"
 
 typedef bool boolean;
 typedef uint8_t byte;