THE historic election of Barack Obama came at a good time for Timothy Greenfield-Sanders and Elvis Mitchell, who photographed and interviewed a number of prominent African-Americans about overcoming the racial divide for an HBO documentary, “The Black List Project.” At a show of the photos at the Brooklyn Museum the other night, the overflow crowd included many of their portrait subjects, including Faye Wattleton, Thelma Golden, Zane, Bill T. Jones and legendary Negro League baseball star Mahlon Duckett. Also on hand: Lou Reed, Jeffrey Wright, Kiki Smith and Credit Suisse CEO and sponsor Paul Calello.