There’s a double-layered sense of self-reflective nostalgia baked into Alexander Payne’s misfit holiday movie “The Holdovers.” Set in 1970, there’s nostalgia for the time period, which is textured and rendered with care and conviction on-screen. But the film itself, a warm, spicy brew of humor, poignancy and irascible charm, also inspires the odd desire to be rewatching it while you’re watching it, a kind of nostalgia for the present moment. That funny feeling is reflected in the plot too, in which a trio of near strangers form an unlikely but indelible bond over Christmas break at a Massachusetts boarding school.