RAWDAT KHURAIM, SAUDI ARABIA-Secretary of State Hillary Rodham Clinton begins a difficult diplomatic assignment Monday in Saudi Arabia, a key U.S. ally.By all accounts, President Obama’s meeting with King Abdullah last year went poorly over misunderstandings on a variety of issues, and now Clinton seeks to rebuild ties.Clinton, who landed in Riyadh on Monday afternoon, is expected to have lengthy meetings with the king, a tough, no-nonsense leader, at a huge tent compound about a 65-minute drive from the capital...