A state appeals panel blocked a man’s bid for a special prosecutor to investigate the police officer who killed his son.The 1st District Appellate Court found Emmett Farmer failed to raise any actual conflicts of interests that prohibited Cook County State’s Attorney Kimberly M. Foxx from filing criminal charges against officer Gildardo Sierra. In 2011, Sierra fired his gun 16 times at Emmett Farmer’s son, Flint, because he said Flint was charging at him with a gun. Flint Farmer had a cell phone in his …