Sil Austin, jazz artist who recorded more than 30 albums and the Top 40 hits “Slow Walk,” “My Mother’s Eyes,” and his signature song “Danny Boy,” died Sept. 1 of prostate cancer in College Park, Ga. He was 71.Austin taught himself how to play the tenor saxophone when he was 12. Four years later, he played “Danny Boy” on “The Ted Mack Amateur Hour,” a performance that caught the attention of Mercury Records. Austin performed all over Europe and Asia, usually traveling with his wife, the Rev. Vernice Austin.