hooks/pre-auto-gc: fix AC detection on OSX Maverick

The output of pmset has been changed to "Now drawing from 'AC Power'"

Change-Id: Id425d3bcd6a28656736a6d2c3096623a3ec053cc

hooks/pre-auto-gc

@@ -35,7 +35,7 @@ elif grep -q "AC Power \+: 1" /proc/pmu/info 2>/dev/null
 then
 	exit 0
 elif test -x /usr/bin/pmset && /usr/bin/pmset -g batt |
-	grep -q "Currently drawing from 'AC Power'"
+	grep -q "drawing from 'AC Power'"
 then
 	exit 0
 elif test -d /sys/bus/acpi/drivers/battery && test 0 = \