restore: call close_old_fds() after mounting /proc

A process can be restored in a new pidns. close_old_fds() opens
the /proc/PID directory. Without this patch we can see errors like this:
(00.333915)      1: Error (util.c:102): Unable to close fd 6: Bad file descriptor
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

cr-restore.c

@@ -1246,9 +1246,6 @@ static int restore_task_with_children(void *_arg)
 		if (restore_finish_stage(CR_STATE_RESTORE_NS) < 0)
 			exit(1);
 
-		if (close_old_fds(current))
-			exit(1);
-
 		if (collect_mount_info(getpid()))
 			exit(1);
 
@@ -1263,6 +1260,9 @@ static int restore_task_with_children(void *_arg)
 		if (mount_proc())
 			exit(1);
 
+		if (close_old_fds(current))
+			exit(1);
+
 		if (root_prepare_shared())
 			exit(1);
 	}