MICKEY CANTOR and Sir Leon Brittan, face to face in the Gatt negotiations, have given a new term to the negotiator's art: a Lithuanian stand off. If at long last they have brokered a deal to satisfy each other and pacify the French, they will earn some sort of reward and Sir Leon may get it. The next reward coming up in Europe (not that everyone would want it) is Jacques Delors' job. The incumbent has stayed on just too long, his authority is dwindling, it is time to go. There is, of course, a candidate from the omnipresent Rentadutchman agency. This is Ruud Lubbers, Holland's prime minister who played host at Maastricht — not quite the recommendation that it was. Giuliano Amato from Italy, another prime minister, has the useful advantage of being the candidate with the least enemies. Clear- ly in the market for an international job of this kind, he tried hard for Jacques Attali's. And Sir Leon? If he comes out of the Gatt talks on speaking terms with the French, he must be fancied. He will have the committed support of his home government, and must hope that this does not count against him.