DAKAR, Senegal — The West African nation of Gabon isn't one of the world's more high-profile countries. So why a state visit by China's leader? That's easy: oil. Burning fuel at a record pace to run an economy in overdrive, China, since late last year, has claimed the No. 2 spot in world oil imports, second only to the United States. And jostling with the world's other oil gulpers, China's leaders are looking far afield for a secure oil supply, locking down tough-term deals with easy-term cash. China, the United States, Japan, Europe and, increasingly, India — all leery of...