Wendy's International Inc., based in Dublin, Ohio, posted a $6.8-million first-quarter loss as its revenue fell 6.6% from a year ago. A year ago, the company earned $16 million. Robert L. Barney, Wendy's chairman and chief executive, called the results "disappointing" but added that he felt the company is recovering. The latest quarterly loss comes on the heels of a $4.93-million loss for all of 1986. "We're rebuilding the business for the long haul, not managing for quarterly earnings," said Barney.