Based on a true story." those are loaded words. Look at the flak hurled at Quiz Show for fiddling with a time frame. By that standard the undeniably affecting Murder in the First, which takes major factual liberties, is bound to get bashed. Here's the true part: Henri Young -- Kevin Bacon in a blistering performance -- hit prison at 17 for stealing five bucks from a post office. In 1938, Henri was thrown into the dungeons of Alcatraz, where he spent more than three years naked and cringing in a…