static int stbi__pic_is4(stbi__context *s,const char *str)
{
   int i;
   for (i=0; i<4; ++i)
      if (stbi__get8(s) != (stbi_uc)str[i])
         return 0;

   return 1;
}
static int stbi__pic_is4(stbi__context *s,const char *str)
{
   int i;
   for (i=0; i<4; ++i)
      if (stbi__get8(s) != (stbi_uc)str[i])
         return 0;

   return 1;
}