“Coup de Torchon” (1981), set to be feted with a one-week revival at Film Forum starting December 1, has to be among the most cynical films ever made. Granted, the competition is stiff and, given the source material, “Pop. 1280” by pulp laureate Jim Thompson, you can’t fault director and screenwriter Bertrand Tavernier for erring on the side of the sardonic, the blasé, and the weary. Still, even the most hard-boiled misanthrope will be taken aback by the ennui that dominates the picture.