Foxconn Technology Group and Belkin both do big business with Apple Inc. Now they’re doing big business with each other. Foxconn Interconnect Technology Ltd., a subsidiary of the Taiwanese company that manufactures iPhones overseas and is planning a $10 billion LCD screen plant in Mount Pleasant, has signed a deal to acquire Belkin International for $866 million in cash. Based in the Los Angeles neighborhood of Playa Vista, Calif., Belkin makes mobile accessories for laptops, smartphones and…