Apple’s reported buyout of mapping software company Poly9 would be at least the fourth acquisition by the iPhone maker this year. Poly9, according to a report in Canadian news site Le Soleil, would bolster Apple’s mapping and location-oriented technology base. Apple kicked off the year by purchasing Quattro Wireless, a company involved in mobile advertising, for an estimated $275 million. In April, Apple was reported to have acquired Siri, a maker of an iPhone app that serves as a personal assistant.”]