As evidenced by The Informant!, it’s a hell of a tricky thing turning real-life pulp into floss sugar. The story of Archer Daniels Midland Co. biochemist-exec-turned-crooked-federal-snitch Mark Whitacre is a tragicomedy. Journalist Kurt Eichenwald spent five years trailing the bipolar fuck-up, and his 2000 book The Informant is so densely,…