MEXICO CITY — Long vilified here as a corrupt oligarch, mega-billionaire Carlos Slim in recent months has become an unlikely champion of Mexico.The telecommunications mogul has emerged as one of President Trump’s most high-profile antagonists south of the border. As Mr. Trump has cracked down on immigration flows, called for a Mexico-financed wall on the border and blamed Mexico for stealing American jobs, Mr. Slim has trashed the wall and said it’s time for his countrymen to chart their economic future without the U.S.
