cpupower: Better detect offlined CPUs

Before, checking for offlined CPUs was done dirty and
it was checked whether topology parsing returned -1 values.
But this is a valid case on a Xen (and possibly other) kernels.

Do proper online/offline checking, also take CONFIG_HOTPLUG_CPU
option into account (no /sys/devices/../cpuX/online file).

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>

tools/power/cpupower/utils/helpers/helpers.h

@@ -96,6 +96,9 @@ struct cpupower_topology {
 		int pkg;
 		int core;
 		int cpu;
+
+		/* flags */
+		unsigned int is_online:1;
 	} *core_info;
 };