Cristian Mungiu’s Norway-set drama about political polarization, “Fjord,” has won the Palme d’Or, handing the Cannes Film Festival ’s top honor for the second time to Mungiu, the Romanian director of “4 Months, 3 Weeks and 2 Days.” At a 79th Cannes Film Festival that saw few films cause a stir, “Fjord” found wide admiration for its engrossing tale of what Mungiu called “left-wing fundamentalism.” It stars Sebastian Stan and Renate Reinsve as Romanian Evangelicals who move to Norway, but soon