Singer R. Kelly told a federal judge Thursday that he won’t testify at his ongoing trial in Chicago on charges that accuse him of child pornography, enticement of minors for sex and fixing his 2008 state trial.The judge raised the issue minutes before attorneys for Kelly and two co-defendants began calling their first witnesses, endeavoring to counter two weeks of government testimony, including from four women who accused Kelly of sexual abuse. Addressing the Grammy Award-winner directly Thursday, U.S. District Judge …