When I met Ousmane Sembene, 81, in his Midtown hotel, he politely asked me if he could smoke his pipe during our interview, but ultimately chose to refrain. This same courteous restraint occasionally expressed itself as cheerful reticence in response to some of my questions. The father of African cinema, Mr. Sembene had arrived from Dakar just the day before to promote “Moolaade,” his rousing, magnificent film about female circumcision.