TOKYO (Reuters) - Mazda Motor Corp said annual profit slid to an eight-year low and that the coronavirus pandemic had resulted in a large build-up in its U.S. car inventories, hobbling efforts to improve its cash flow.Japan's No. 5 automaker refrained from giving an earnings forecast for this business year and confirmed it had tapped lenders for loans to ride out the outbreak which has pummelled car demand worldwide.Annual operating profit almost halved to 43.6 billion yen ($408 million) for..