LONDON, Feb 19 : U.S. futures and European stocks fell on Thursday as investors zeroed in on company earnings while tensions between the United States and Iran kept markets on edge and supported oil prices and gold. Europe's STOXX 600 index dropped 0.6 per cent as shares in planemaker Airbus and miner Rio Tinto slid after their earnings reports underwhelmed the market. The index hit a record the previous day as a rally in defence and banking shares helped investors shake off worries about