Update cpu_

some fixes for guest_nice

plugins/system/cpu_

@@ -87,6 +87,9 @@ emit_values()
 {
 	while read key user nice system idle iowait irq softirq steal guest guest_nice
 	do
+		if [ "$guest_nice" == "" ]; then
+			guest_nice=0
+		fi
 		[ "$key" != "$1" ] && continue
 		cat <<EOF
 system.value $system
@@ -98,6 +101,7 @@ irq.value $irq
 softirq.value $softirq
 steal.value $steal
 guest.value $guest
+guest_nice.value $guest_nice
 EOF
 	done < /proc/stat
 }