Fix a signed/unsigned comparison warning (#27)
Fix a signed/unsigned comparison warning (#27)

The signed value in comparison is always positive, so it's safe to just cast it to unsigned.
szabadka/guetzli,google/guetzli,ianhuang-777/guetzli,dloeng/guetzli,dloeng/guetzli,guanzidashu/guetzli_ios_metal,guanzidashu/guetzli_ios_metal,google/guetzli,guanzidashu/guetzli_ios_metal,ianhuang-777/guetzli,google/guetzli,ianhuang-777/guetzli,google/guetzli,dloeng/guetzli,ianhuang-777/guetzli,szabadka/guetzli,guanzidashu/guetzli_ios_metal,szabadka/guetzli