A man designated as a sexual predator 30 years after his conviction for rape does not have a case for a violation of his rights, a federal appeals court held Wednesday.The 7th U.S. Circuit Court of Appeals rejected the argument that the Illinois Sex Offender Registration Act — at least when it comes to Anthony Johnson — runs afoul of the U.S. Constitution’s ex post facto clause.That clause prohibits retroactively increasing the penalty for a crime after it is committed or retroactively criminalizing an …