restore: restore pgid in two phases

As described in the previous patch, process group leaders are restored in
the first phase, then all other processes restores pgid.
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -705,9 +705,13 @@ static int restore_task_with_children(void *_arg)
 			exit(1);
 	}
 
+	if (me->pgid == me->pid.virt)
+		restore_pgid();
+
 	futex_dec_and_wake(&task_entries->nr_in_progress);
 	futex_wait_while(&task_entries->start, CR_STATE_FORKING);
 
+	if (me->pgid != me->pid.virt)
 		restore_pgid();
 
 	if (me->state != TASK_HELPER) {