code: private int calcFuByWait(MentsuComp comp, Tile last) {
          if (comp.isKanchan(last) || comp.isPenchan(last) || comp.isTanki(last)) {
              return 2;
          }
  
          return 0;
      }
docs: 待ちの種類による可符
  
  @param comp
  @param last
  @return