Every zombie fable boils down to insatiable hunger, both as it pertains to the undead and the forms it takes among the living. That part is where each story diverges. In George A. Romero’s 1978 masterpiece “Dawn of the Dead,” survivors took refuge in a mall, but they also hoarded its supplies. Zack Snyder’s contribution to the genre accentuates desperation. In his 2004 remake of “Dawn of the Dead” the zombies are sprinting, roaring killing machines that consume America before the opening credits roll. In their wake aftermath, hopelessness proves to be the slow, shambling, inescapable inevitability that does in everyone else. His latest, “Army of the Dead,” is not that film’s sequel. It could have been, since the main hero is a veteran of the so-called “zombie wars.” But the desperation evoked here is different, and relatable to everyone on the losing side of America’s expanding wealth gap. That describes almost everyone, including sidelined mercenary Scott Ward (Dave Bautista). With his friends Maria Cruz (played by Ana de la Reguera) and fellow soldier-for-hire Vanderohe …