MADRID — Thibaut Courtois was Real Madrid’s top signing after Cristiano Ronaldo joined Juventus last year. Real Madrid felt its only real need at the time was to improve the goalkeeping position, and it tried to do that by bringing in the man voted as the best at that position at the World Cup that year. With Courtois in goal, the lingering doubts about Madrid’s goalkeeping position would finally be put to rest. A year later, though, Madrid is again facing a goalkeeping crisis. Courtois was booed by the Santiago Bernabéu crowd in the team’s 2-2 draw against Club Brugge in the Champions League on Tuesday, then was strangely replaced by coach Zinedine Zidane at halftime after conceding two goals from three shots against the Belgian club. Zidane gave few hints after the game about what was wrong with Courtois, saying he wasn’t feeling well and couldn’t continue. The club later said stomach problems kept the Belgium goalkeeper from returning to the game. Courtois was substituted by recently signed French goalkeeper Alphonse Areola, who has quickly become a fan favorite after some good performances in goal, including against Brugge, when he made a great save while facing a one-on-one situation…