Reject JPEGs with unexpectedly large coefficient values.
Reject JPEGs with unexpectedly large coefficient values.

Large coefficient values usually imply that pixel values will be
clipped, so we will be trying to optimize a suboptimal representation of
the image. Also, handling of very large coefficient values is rife with
problems (overflows when handling unwuantized values, inability to
encode at some quantization levels, etc.).

Fixes oss-fuzz/970 and oss-fuzz/971.

google/guetzli,google/guetzli,google/guetzli,szabadka/guetzli,guanzidashu/guetzli_ios_metal,szabadka/guetzli,ianhuang-777/guetzli,dloeng/guetzli,dloeng/guetzli,guanzidashu/guetzli_ios_metal,dloeng/guetzli,ianhuang-777/guetzli,guanzidashu/guetzli_ios_metal,szabadka/guetzli,guanzidashu/guetzli_ios_metal,google/guetzli,ianhuang-777/guetzli,ianhuang-777/guetzli