VIENNA — For years, strongmen and autocrats had a novel weapon in their hunt for political enemies. They used Interpol, the world’s largest police organization, to reach across borders and grab them — even in democracies. An award-winning Venezuelan journalist was detained in Peru. An Egyptian asylum-seeker was stopped in Australia. And Russia has tried repeatedly to secure the arrest of William F. Browder, a London-based human rights campaigner. In response, Interpol has toughened oversight of