BAE Systems Plc, Europe’s biggest defense company, posted a 13 percent gain in full-year earnings as U.S. military spending picked up and its planes and weapons were deployed in wars in Syria and Yemen. Underlying earnings before interest, tax and amortization rose to 1.91 billion pounds from 1.68 billion pounds a year earlier, the London-based maker of Eurofighter warplanes said in a statement Wednesday.