Former U.S. Secretary of State and presidential candidate Hillary Clinton will serve as the commencement speaker at her alma mater, Wellesley College, this spring, a school spokesman said. Clinton graduated from the Boston women’s liberal arts college in 1969. Her speech on May 26 will come nearly a half-century after her famous address to her fellow graduating seniors, the first time a student had ever spoken at commencement. The former First Lady was active on campus during her time at Wellesley,…