cgroup: remove the restriction of subset-of-root-set

At one point in the cgns patchsets I had removed this, but somehow it got
lost in the shuffle. Since we support this now, let's remove this
restriction.
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/cgroup.c

@@ -868,21 +868,6 @@ static int dump_sets(CgroupEntry *cg)
 		if (set == criu_cgset)
 			continue;
 
-		/*
-		 * Check that all sets we've found that tasks live in are
-		 * subsets of the one root task lives in
-		 */
-
-		pr_info(" `- Dumping %d set (%d ctls)\n", set->id, set->n_ctls);
-		if (!cg_set_compare(set, &root_cgset->ctls, CGCMP_ISSUB)) {
-			pr_err("Set %d is not subset of %d\n",
-					set->id, root_cgset->id);
-
-			list_for_each_entry(ctl, &set->ctls, l)
-			pr_info("   `- %s of %s\n", ctl->name, ctl->path);
-			return -1;
-		}
-
 		/*
 		 * Now encode them onto the image entry
 		 */