General Mills is marketing a new international flavor of yogurt in a bid t or evive sales. The make rof Cheerios cereal, Yoplait yogurt and other packaged foods hails the brand, dubbed “Oui,” as the arrival of “French-style ”yo gurt in the U.S. Like the yogurts that channel the heritage so f other countries, however, the compan ys ays there is no official definition for French yogurt. The attempt to cultivate a trendy new yogurt comes as overall U.S. sales are slumping. Yogurt sales ar ed ow n3 percent so far thi sy ear compar edt o a year ago, according to Nielsen. General Mills has been particularly hard-hit ,w ith its yogurt sales down 20 percent in it sl atest quarter.