sfree(NULL) is ok

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.c b/fio.c
index 03dc6cc..ae62d23 100644
--- a/fio.c
+++ b/fio.c
@@ -1694,8 +1694,7 @@
 
 	cgroup_kill(cgroup_list);
 	sfree(cgroup_list);
-	if (cgroup_mnt)
-		sfree(cgroup_mnt);
+	sfree(cgroup_mnt);
 
 	fio_mutex_remove(startup_mutex);
 	fio_mutex_remove(writeout_mutex);