By Julian Linden NEW YORK, Aug 31 (Reuters) – Victoria Azarenka dropped her first set of the tournament on Saturday but recovered to book her place in the last 16 at the U.S. Open after two former grand slam champions were sent packing. A finalist last year and one of the favourites to win the title this season, a feisty Azarenka overcame a shaky start to beat Alize Cornet of France 6-7(2) 6-3 6-2 after Petra Kvitova and Svetlana Kuznetsova crashed out. …