[gnoduino] Fixed missing NOT_AN_INTERRUPT constant in digitalPinToInterrupt()

[Lucian Langa <lucilanga src gnome org>]

commit 7b82354646af94d1e3a021649b31652c1254f088
Author: Cristian Maglie <c maglie bug st>
Date:   Tue Oct 21 16:55:37 2014 +0200

    Fixed missing NOT_AN_INTERRUPT constant in digitalPinToInterrupt()
    
    Fixes #2379

 hardware/arduino/cores/arduino/Arduino.h |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/hardware/arduino/cores/arduino/Arduino.h b/hardware/arduino/cores/arduino/Arduino.h
index a136d6c..2e69019 100755
--- a/hardware/arduino/cores/arduino/Arduino.h
+++ b/hardware/arduino/cores/arduino/Arduino.h
@@ -171,6 +171,8 @@ extern const uint8_t PROGMEM digital_pin_to_timer_PGM[];
 #define NOT_A_PIN 0
 #define NOT_A_PORT 0
 
+#define NOT_AN_INTERRUPT -1
+
 #ifdef ARDUINO_MAIN
 #define PA 1
 #define PB 2