veth: fix off by one error

0e869bf introduces this bug, which chops
off the last character of the external veth name, and then subsequent
move_veth_to_bridge() calls fail:

(01.012478) Error (criu/net.c:1758): Can't get index of veth69A67O: No such device

travis-ci: success for veth: fix off by one error
Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
CC: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/net.c

@@ -916,7 +916,7 @@ static void veth_peer_info(NetDeviceEntry *nde, struct newlink_req *req)
 		char *aux;
 
 		aux = strchrnul(val, '@');
-		addattr_l(&req->h, sizeof(*req), IFLA_IFNAME, val, aux - val - 1);		
+		addattr_l(&req->h, sizeof(*req), IFLA_IFNAME, val, aux - val);
 	}
 }