One happy byproduct of the oversaturation of things ghoulish and garish that comes our way this time every year is the reliable arrival on home video of films at least tangentially related to Halloween. And so it is that Warner Archive has just bestowed on fright lovers two horror classics: “Dr. Jekyll and Mr. Hyde” (1931) and “Mark of the Vampire” (1935)—each glowingly restored in 4K and available on Blu-ray.