Only some of the crowd greeting French designer Jean-Paul Gaultier at the Brooklyn Museum, wore his clothes, easily identified by the tab on the back. But many chose the occasion of the opening of a lavish exhibition, “The Fashion World of Jean-Paul Gaultier: From the Sidewalk to the Catwalk,” to pay tribute, riffing on his most camp and louche looks without actually wearing HIS designs. That’s to be expected for the man who gave Madonna the pointy cone bra! But upstairs on the museum’s fifth floor, rooms fitted with mannequins whose facial expressions move in delight or dismay display his art in a spectacular show to rival the splendid Alexander McQueen at the Metropolitan Museum a few seasons back.