The rapper, 49, claimed that Jay-Z’s entertainment company, Roc Nation, tried to keep him out of the star-studded hip-hip mashup that also included Eminem, Snoop Dogg, Kendrick Lamar, Dr. Dre and Mary J. Blige. “They wanted to leave me out of it. They didn’t want me there,” 50 Cent told the Hollywood Reporter in an interview published Wednesday. Jay-Z, 54, …