WINSTON-SALEM, North Carolina (Reuters) – Actor Andy Griffith, beloved as a small-town sheriff on the popular television program "The Andy Griffith Show," died of a heart attack, according to his death certificate. Griffith, 86, died on Tuesday at his home in coastal Manteo, North Carolina. According to his death certificate, he was buried in a family cemetery, an employee at the Dare County Register of Deeds Office said on Thursday. The certificate noted that Griffith had suffered for years from coronary artery disease, hypertension and hyperlipidemia, a condition related to high cholesterol. …