HAM IT UP: Arnold is finally coming to Buena Park's Movieland Wax Museum. Schwarzenegger you say? . . . Wrong. He's already there. Newly waxed will be Arnold Ziffel, the 1960s' couch potato pig on TV's "Green Acres." The museum will also toss in wax figures of series stars Eva Gabor and Eddie Albert, who have RSVP'd for the June 16 unveiling. Yes, Arnold will be there--though not the original. The reruns outlived him.