J.D. Salinger is remembered today as a reclusive misanthrope. Jerome Charyn''s Salinger is a young American WWII draftee assigned to the Counter Intelligence Corps, a band of secret soldiers who trained with the British. A rifleman and an interrogator, he witnessed all the horrors of the war - from the landing on D-Day to the first Allied entry into a Bavarian death camp, where corpses were piled like cordwood. Maladjusted to civilian life, he lived like a ''spook,'' with the ghosts of the murdered inside his head, and stories to tell.