SAN FRANCISCO — To call Landen Roupp headstrong would be an understatement. There are times on the mound when he conjures Madison Bumgarner, swiping a cleat against the slab and glaring at an opposing hitter whose very presence in the box seems a personal affront. There are times when he conjures Ryan Vogelsong, refusing to yield even if it means grinding through one 3-2 count after another and treating every open base as if he’s a nervous talk show audience coordinator with seats to fill.