By Aziz El Yaakoubi and Eduardo Baptista RIYADH (Reuters) -Chinese President Xi Jinping began a visit to Saudi Arabia on Wednesday that Beijing said marked its biggest diplomatic initiative in the Arab world, as Riyadh expands global alliances beyond a long-standing partnership with the West. The meeting between the global economic powerhouse and Gulf energy giant comes as Saudi ties with Washington are strained by U.S. criticism of Riyadh’s human rights record and Saudi support for oil output curbs before the November midterm elections. The White House said Xi’s visit was an example of Chines…