The leaders of Saudi Arabia and Egypt successfully lobbied President Trump to shift U.S. policy in Libya and reach out to the general leading an offensive against the country’s United Nations-backed government, a senior U.S. administration official and two Saudi officials said. In early April, Saudi Crown Prince Mohammed bin Salman and Egyptian President Abdel Fattah Al Sisi urged Mr. Trump to back Gen. Khalifa Haftar, whose forces are seeking to capture the Libyan capital Tripoli amid a long-running battle for control of…