In 1989, actors Keanu Reeves and Alex Winter played Bill and Ted, two friend who undertook an “excellent adventure.” Now, they’ve reteamed on Broadway as Estragon and Vladimir, two friends examining the absurdity of life in Samuel Beckett’s masterpiece “Waiting for Godot.” They talk with Tracy Smith about their own friendship; how Alex, at the height of his fame, walked away from acting; and what Keanu finds risky about live theater.