AUSTIN, Texas — A person familiar with the situation says Lance Armstrong confessed to Oprah Winfrey during an interview Monday that he used performance-enhancing drugs to win the Tour de France. The person spoke on condition of anonymity because the interview is to be broadcast Thursday on Winfrey’s network. Armstrong was stripped of all seven Tour titles last year in the wake of a voluminous U.S. Anti-Doping Agency report that portrayed him as a ruthless competitor, willing to go to any lengths to win the prestigious race. USADA chief executive Travis Tygart labeled the doping regimen allegedly carried out by …