Fix an inverted cgroup exit check

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/cgroup.c b/cgroup.c
index b65b1fb..29d89dd 100644
--- a/cgroup.c
+++ b/cgroup.c
@@ -150,7 +150,7 @@
 {
 	if (cgroup_check_fs(td))
 		return;
-	if (!td->o.cgroup_weight && td->o.cgroup)
+	if (!td->o.cgroup_weight && !td->o.cgroup)
 		return;
 
 	cgroup_del_pid(td);