STOCKHOLDER AGREEMENT by and among CEMENTOS ARGOS S/A, ARGOS SEM, LLC, VALLE CEMENT INVESTMENTS, INC., SUMMIT MATERIALS, INC., and solely for the limited purposes of Sections 1.1, 1.2, 2.1, 2.2, 4.1, 4.5(j), 4.5(k), 4.5(l), 4.5(m), 4.6, 4.7 and...