NIAMEY, Niger — A convoy carrying ousted Libyan leader Moammar Gadhafi’s son al-Saadi has crossed into neighboring Niger, a spokesman for Niger’s government said Sunday, the highest profile former regime figure to flee to the landlocked African nation. Al-Saadi, the fugitive ruler’s 37-year-old son, entered Niger in a convoy with nine other people, said Niger Justice Minister Amadou Morou.