“I have already lived my death — all that’s left is to make the movie.” So says celebrated Argentine-Brazilian filmmaker Héctor Babenco in a documentary that, sure enough, attempts to bring closure to a life already concluded. After three decades of living with cancer and related complications, Babenco passed away in 2016 aged 70; directed by his widow Bárbara Paz, “Babenco: Tell Me When I Die” movingly serves as both valedictory and valentine, channeling and preserving the spirit of an artist who vocally feared that his life’s work hadn’t been completed. “Tell Me When I Die” may technically be Paz’s first film rather than the eponymous director’s last, but an intimate air of collaboration colors the whole monochrome affair: As a portrait of a dying man trying to at least co-direct his own farewell, it’s so sorely tender as to be a little discomfiting.