Most comedies rely on a certain amount of established tropes: the obsessive best friend, the stereotyped psychotherapist, the randy 20-year-old. Besides offering comfort, this kind of familiarity can function like a reassuring blanket wrapped around such potentially discomforting issues as female sexuality, the Grim Reaper and what it means to be a 40-year-old woman trying to make sense of a messy life. Established Spanish actress Aina Clotet ’s “ Viva ” (given the anodyne English title “Alive”) is all these things, fleshed out by a flawed protagonist faced with the potential recurrence of breast cancer shortly after a partial mastectomy.  Clotet — director, co-writer and star — indeed makes Nora “alive,” more than most of the one-dimensional side characters, but whether she succeeds in creating a role compelling enough to balance out the overfamiliarity of well-worn formulas will very much depend on individual affinities.…