If there’s one film magazine connected with the Cannes festival, it’d probably be Positif or Cahiers du Cinema, French journals whose passionate seriousness perfectly suits the movies that usually show here. This year, though, the festival’s journal of record should be the American horror-movie mag Fangoria. The official Cannes selection has included all manner of genre films: a sexy vampire shocker , a guns-n-guts crime film and two gory psycho-thrillers about devoted mothers gone bad .