cgroup: call fini_cgroup() on error paths

Currenlty if criu fails before prepare_cgroup_properties(),
cgyard isn't umounted.

I think it's déjà vu, but it isn't :)

commit 28b0e16d
Author: Andrew Vagin <avagin@openvz.org>
Date:   Mon Aug 25 14:29:00 2014 +0400

    cgroup: call fin_cgroup() on error paths

Cc: Tycho Andersen <tycho.andersen@canonical.com>
Cc: Saied Kazemi <saied@google.com>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -1850,10 +1850,8 @@ static int restore_root_task(struct pstree_item *init)
 
 	write_stats(RESTORE_STATS);
 
-	if (!opts.restore_detach && !opts.exec_cmd) {
-		fini_cgroup();
+	if (!opts.restore_detach && !opts.exec_cmd)
 		wait(NULL);
-	}
 
 	return 0;
 
@@ -1875,6 +1873,7 @@ out_kill:
 	}
 
 out:
+	fini_cgroup();
 	stop_usernsd();
 	__restore_switch_stage(CR_STATE_FAIL);
 	pr_err("Restoring FAILED.\n");