Oscar-winning actor Michael Douglas made a cameo appearance yesterday in Manhattan federal court to bail out his troubled son, Cameron, who pleaded guilty to drug-trafficking charges earlier this week. The session was held in a closed courtroom and Cameron’s case file was sealed, suggesting that he’s cooperating with the feds. His dad and lawyers refused to comment, reports The Post’s Bruce Golding. Cameron, who faces 10 years in jail, was behind bars at the Metropolitan Correctional Center last night.