Callback fiasco: always include Arduino.h before including Callback

Author: facchinm

cores/arduino/USB/PluggableUSBDevice.h

@@ -18,6 +18,8 @@
 #ifndef PLUGGABLEUSBDEVICE_H
 #define PLUGGABLEUSBDEVICE_H
 
+#include "Arduino.h"
+
 /* These headers are included for child class. */
 #include "USBDescriptor.h"
 #include "USBDevice_Types.h"

cores/arduino/USB/USBCDC.h

@@ -18,6 +18,8 @@
 #ifndef USBCDC_H
 #define USBCDC_H
 
+#include "Arduino.h"
+
 /* These headers are included for child class. */
 #include "USBDescriptor.h"
 #include "USBDevice_Types.h"

libraries/USBMSD/PluggableUSBMSD.h

@@ -19,6 +19,7 @@
 #define USBMSD_H
 
 /* These headers are included for child class. */
+#include "Arduino.h"
 #include "USBDescriptor.h"
 #include "USBDevice_Types.h"
 #include "platform/Callback.h"