Litton Industries Inc. and Dresser Industries Inc. have agreed to spin off oil field services units into a new company that will be jointly owned by Litton and Dresser. The new firm will be based in Houston and will have annual revenue of about $550 million . . . Elders IXL, the Australian brewing concern, plans to acquire control of Carling O'Keefe Ltd., one of Canada's largest breweries, in a deal worth about $148 million, Carling's principal owner said.