Peter Bart and Mike Fleming Jr. worked together for two decades at Daily Variety. In this occasional column, two old friends get together and grind their axes, mostly on the movie business. FLEMING: Daniel Day-Lewis' retirement announcement begs the question: who takes over as Greatest Living Actor? If you had asked me who held that title two weeks ago, it would have been a tossup between DDL and Denzel Washington, and those guys will have one last chance to decide it…