Unlike Renee Zellweger in “Bridget Jones’s Diary,” Hollywood queen Julia Roberts won’t pig out and fatten up for her new flick, “America’s Sweethearts” — which requires her to look porky! Julia refused, saying she’ll wear a “fat suit” instead! (What a DIVA! First she refuses to grow breasts for “Erin Brockovich” . . . and now THIS!?)