EXCLUSIVE: Damon Lindelof’s Watchmen is adding more star power to its cast. Oscar winner Jeremy Irons has been tapped for a lead role in the HBO pilot, a take on Alan Moore and Dave Gibbons’ iconic limited comic series. He joins previously cast Regina King, Don Johnson, Tim Blake Nelson, Louis Gossett Jr., Adelaide Clemens and Andrew Howard. Set in an alternate history where "superheroes” are treated as outlaws, Watchmen embraces the nostalgia of the original…