BENGHAZI, LIBYA — Malik Muhammad al-Mabrouk sat two weeks ago in a darkened corner of the Uzu Hotel cafe lounge, the screen of his propped-up iPad illuminating his face. Notepad, pen and cellphone at the ready, and wearing his trademark beige photographer’s vest, he was preparing to interview a former opposition leader who recently returned to Libya after 30 years in exile. Nothing unusual for a working journalist, except that his deadline was also his bedtime: Malik is 14 years old.