cgroups: add monitor_cgroup member

src/lxc/cgroups/cgfsng.c

@@ -2569,6 +2569,7 @@ __cgfsng_ops__ static bool cgfsng_data_init(struct cgroup_ops *ops)
 		return false;
 	}
 	ops->cgroup_pattern = must_copy_string(cgroup_pattern);
+	ops->monitor_pattern = must_copy_string("lxc.monitor");
 
 	return true;
 }

src/lxc/cgroups/cgroup.c

@@ -76,6 +76,7 @@ void cgroup_exit(struct cgroup_ops *ops)
 
 	free(ops->cgroup_pattern);
 	free(ops->container_cgroup);
+	free(ops->monitor_pattern);
 
 	for (it = ops->hierarchies; it && *it; it++) {
 		char **ctrlr;

src/lxc/cgroups/cgroup.h

@@ -92,6 +92,7 @@ struct cgroup_ops {
 	char **cgroup_use;
 	char *cgroup_pattern;
 	char *container_cgroup;
+	char *monitor_pattern;
 
 	/* @hierarchies
 	 * - A NULL-terminated array of struct hierarchy, one per legacy