Clear up warnings, add support for rating values.

source/pc/stb_image.h

@@ -1235,18 +1235,6 @@ stbi_inline static stbi_uc stbi__get8(stbi__context *s)
    return 0;
 }
 
-stbi_inline static int stbi__at_eof(stbi__context *s)
-{
-   if (s->io.read) {
-      if (!(s->io.eof)(s->io_user_data)) return 0;
-      // if feof() is true, check if buffer = end
-      // special case: we've only got the special 0 character at the end
-      if (s->read_from_callbacks == 0) return 1;
-   }
-
-   return s->img_buffer >= s->img_buffer_end;
-}
-
 static void stbi__skip(stbi__context *s, int n)
 {
    if (n < 0) {