INGLEWOOD, Calif. — “And now, ladies and gentlemen, Hollywood Park belongs to you,” the race caller, Joe Hernandez, said over the public-address system on June 10, 1938. Among the 40,000 people who came for opening day at Southern California’s newest racetrack were the era’s biggest film stars, including Al Jolson, Joan Crawford, Milton Berle, Claudette Colbert, Bob Hope and Barbara Stanwyck.