The Metropolitan Opera’s funding has fallen flat. The cash-strapped New York cultural institution is laying off staff, chopping high-ranking executives’ salaries, postponing a new show and possibly selling off two murals worth $55 million, according to a report. Peter Gelb, the Met’s general manager, announced the hefty cutbacks Tuesday, moves he said he was forced to make as a funding deal with Saudi Arabia looks like it might be turning sour. “I have to show we can finance the Met going