Lifted from his poem “Flowers of Evil,” the Charles Baudelaire quote that opens “ Cantona ” — “I am the wound and the knife/I am the blow and the cheek/I am the limbs and the wheel/Victim and executioner” — would seem like overkill in a documentary about pretty much any sporting figure besides Eric Cantona . At the outset of David Tryhorn and Ben Nicholas ‘ glossy, enthralled portrait of the legendary French soccer player and culture-spanning icon, however, it strikes exactly the right note for