Today on TCM’s “Summer Under the Stars,” it’s a 24-hour helping of movies starring or featuring Eva Marie Saint. One of her finest films arrives at 6 p.m. ET, when TCM televises 1954’s On the Waterfront, in which she stars opposite Marlon Brando. But watch, also, for another, which director Brad Bird, guest co-host of TCM’s Saturday night showcase “The Essentials,” makes room for an Alfred Hitchcock movie, 1959’s North by North