Mirror, mirror on the wall, is Rupert Sanders’ retelling of the classic fable, “Snow White and the Huntsman,” the slickest of them all? Indeed ... it is all that and a bag of poisoned apple chips.In one of the film’s signature scenes, Snow White (Kristen Stewart) and The Huntsman (Chris Hemsworth) confront a hulking Troll with gnarled, wood-like skin.The Troll was added digitally after princi…