Home prices in the five-county region were up 5.1 percent compared with a year ago, CoreLogic reported Wednesday. Prices also were up 1.1 percent from May. “The growth in sales is slowing down, and this is not due to lack of affordability, but rather a lack of inventory,” said Frank Nothaft, the chief economist for CoreLogic. The Winston-Salem-area housing market shifted slightly more in the favor of sellers during June, according to CoreLogic, national real-estate research company.