By Daina Beth Solomon, Kylie Madry and Lizbeth Diaz MEXICO CITY (Reuters) -A magnitude 7.6 earthquake struck western Mexico on Monday on the anniversary of two devastating temblors, killing at least two people, damaging buildings, knocking out power and sending residents of Mexico City scrambling outside for safety. Two died in the Pacific port of Manzanillo, authorities said, one crushed by the facade of a department store while another was found dead at a mall. Videos on social media showed the roof of the mall collapsed into the top floor, a gym, as people yelled for help. Authorities also …