(Adds details, share movement) July 30 (Reuters) - Mondelez International Inc reported a better-than-expected quarterly profit, helped by lower costs, and the maker of Cadbury chocolate and Oreo cookies boosted its share buyback plan by $6 billion. The company's shares rose 2.6 percent in premarket trading on Thursday, after it also raised its forecast for 2015 revenue growth. Mondelez said it expects core net revenue to grow by at least 3 percent for the year, up from its prior forecast of at least 2 percent growth. The company said its buyback plan, under which... More