Removed SetSystemClockPrescaler() macro, the clock_prescale_set() avr-libc macro has been corrected in recent avr-libc versions

Demos/USBtoSerial/USBtoSerial.c

@@ -72,8 +72,8 @@ int main(void)
 	MCUSR &= ~(1 << WDRF);
 	wdt_disable();
 
-	/* Disable Clock Division */
-	SetSystemClockPrescaler(0);
+	/* Disable clock division */
+	clock_prescale_set(clock_div_1);
 
 	/* Hardware Initialization */
 	LEDs_Init();

Demos/USBtoSerial/USBtoSerial.h

@@ -40,6 +40,7 @@
 		#include <avr/io.h>
 		#include <avr/wdt.h>
 		#include <avr/interrupt.h>
+		#include <avr/power.h>
 
 		#include "Descriptors.h"
 		#include "RingBuff.h"