Stop watchdog before attempting reboot on Teensy 2.0

teensy/pins_teensy.c

 	#endif
 }
 
+#ifndef WDFR
+#define WDFR 3
+#endif
 
 void _reboot_Teensyduino_(void)
 {
 	cli();
+	// stop watchdog timer, if running
+	MCUSR &= ~(1<<WDFR);
+	WDTCSR |= (1<<WDCE);
+	WDTCSR = 0;
 	delayMicroseconds(5000);
 	UDCON = 1;
 	USBCON = (1<<FRZCLK);