Somewhere on the incoherent pu pu platter that is Cameron Crowe’s “Aloha,” a nifty romantic comedy congeals and shrivels, inexplicably untouched.Crowe — who gave the world such deathless lines as “You had me at ‘Hello,’ ” the man who put the boom box in Lloyd Dobler’s defiantly upstretched arms — spends so much time running away from his roots in “Aloha” that he misses the point of his own movie.