A giant ''like'' icon made popular by Facebook is seen at the company's new headquarters in Menlo Park, California January 11, 2012. Credit: Reuters/Robert Galbraith By Ben Klayman and Gerry Shih DETROIT/SAN FRANCISO | Tue Jul 3, 2012 4:47pm EDT (Reuters) - General Motors Co and Facebook Inc are discussing the return of the U.S. automaker as a paid advertiser almost two months after GM said it would stop running ads on the social networking website, sources close to the situation said on Tuesday. Although the two companies remain far from reaching an agreement, Facebook…