FLUSHING MEADOWS, N.Y. — The gate-minders at Court 13 erected barriers to control the ticket-holders racing over from 10,103-seat Louis Armstrong Stadium, desperate for a spot on bleachers designed to hold 584. Those who made it inside Court 13 before an usher shouted, “No more people!” got the rare privilege of watching world-class tennis in a high school-size venue Thursday at the U.S.