PARIS (Reuters) - Johnny Hallyday, a singer known as the “French Elvis” whose cowboy swagger and gravelly voice helped popularize rock ‘n roll in his country, has died at 74 after a battle with cancer, the office of the French president said on Wednesday. “For more than 50 years, he was a vibrant icon,” President Emmanuel Macron’s office said in a statement. Sponsored Hallyday is often credited with sales of more than 100 million albums over the decades.