PORTUGAL'S largest builder Mota-Engil has signed four contracts worth a total 975 million euros ($1.06 billion) in Angola and Mexico, strengthening the order book in Africa and Latin America - its main markets - and causing its shares to rise. The company said its new contracts with the Angolan government included the Corimba waterfront construction and social housing in the capital Luanda, as well as a border post on Angola's frontier with the Democratic Republic of Congo. The three Angolan contracts are worth around 875 million euros. In Mexico, the builder will participate in the construction of a road on…