Brent Lang Executive Editor Oliver Stone is talking about “Lula,” his new documentary about Brazilian President Luiz Inácio Lula da Silva, which is premiering at the Cannes Film Festival, when the conversation turns to American politics. The conspiracy-minded director, who’s never seen a grassy knoll without glimpsing a second gunman on it, is drawing an analogy between Lula’s political travails, involving a corruption investigation that led to a 580-day prison stint, and those of Donald Trump. That’s when the film’s publicist interjects and politely tries to steer the topic back to the documentary.