BY William S. Burroughs. Viking, $6.95. Since the book is labeled a novel, one is obliged to look for some kind of continuity in it, which is unfortunate. The chapters, taken as individual sketches, are inventive, glitteringly clever attacks on various regrettable aspects of contemporary life. Viewed as a whole, they become the diatribe of an aging homosexual who would destroy the world because his own life is less gay than it used to be.