Adriano Valerio’s documentary “Casablanca,” which will world premiere on Thursday at Venice Days, has been acquired by Salaud Morisset for world sales. Variety has been given an exclusive clip from the film. “Casablanca” follows Fouad, a Moroccan living in Italy without papers, and Daniela, a former drug-addict from Apulia’s upper middle-class, who find each other …