Billionaire and Home Depot founder Kenneth G. Langone is giving a $100 million donation to New York University Medical Center. The amount matches a contribution he gave the facility in 1999. NYU representatives said that it will use the funds to start a campaign to raise $1 billion for a new hospital pavilion. In return for the donation, the university plans to rename the medical center the N.Y.U. Langone Medical Center, effective immediately.