By Julien Pretot and Krystal Hu BEIJING (Reuters) -China’s Eileen Gu got her maiden Olympics off to a dream start as the U.S. born teenager landed a tricky jump to become the first freeski Big Air champion at the Beijing Games, taking the host country to the top of the medals table on Tuesday. With the Shougang steel mill in the backdrop, Gu landed in the final run a 1620, a trick only Tess Ledeux had achieved in competition before. The Frenchwoman settled for silver. Ledeux was leading after two runs but pressure got to the Big Air World Cup leader and she struggled on her final jump, ending …