George Segal, Jacqueline Bisset and Robert Morley top the bill of fare in this food- and fun-filled mystery garnished with wit. Segal plays a glib fast-food tycoon and Bisset is his ex-wife, a pastry chef who may become the last course in an enigmatic killer's banquet of death. Morley has a tasty field day as an acerbic gourmet magazine publisher whose cascading series of chins and stomachs bear witness to his love of fine dining. But t