“A Merry Friggin’ Christmas” (2014) was one of Robin Williams’ last movies. I know you might feel guilty about not liking it, but that’s OK, because this movie isn’t that good. (I can imagine the conversation that went on in some Hollywood development meeting: “Picture ‘Planes, Trains and Automobiles’ meets ‘Christmas Vacation.’ It’s pure gold, I tell ya!”) So anyway, the guy from “Community” stars as the prodigal son of a dysfunctional family, of which Williams is the foul-mouthed, boozy patriarch. Cliched Christmas hijinks ensue. Road movie hijinks ensue. Sloppy plot construction and awkwardly staged family melodrama ensue. Sorry, Robin.