The Hamptons International Film Festival announced Monday that Stuart Match Suna, one of its founders, will step down as chairman after 18 years. Additionally, the festival's board of directors elected Alec Baldwin and Randy Mastro to serve as the new co-chairmen. Mr. Suna will continue as chairman emeritus.For the past decade, Mr. Baldwin and Mr. Mastro have served on the board of the festival, now in its 23rd year. They will begin their tenure as co-chairmen after this year’s festival in October. Mr.