Fix libjpeg_turbo svn r64 libjpeg6b compat issue

Fix libjpeg_turbo svn r64 libjpeg6b compat issue

Make the fast path Huffman decoder fallback to the slow decoding path if
the Huffman decoding bit sentinel > 16, this to match libjpeg6b decoding
by reproducing the exact behavior of jpeg_huff_decode().

When this sentinel check is missing (see bug), libjpeg_turbo can produce
two (or more) different decoded images for the same input data depending
on how transport systems (eg., networks) packetize the data for delivery
to end-systems, web browsers for example.

Note: libjpeg6b produces the same decoded image, irrespective of how the
input data is placed in network packets. This fix makes libjpeg_turbo do
the same for compat with libjpeg6b.

TBR=darin@chromium.org
BUG=chromium:398235

[noel chromium, 2015-04-27 11:36:18]

Submitted as
http://src.chromium.org/svn/trunk/deps/third_party/libjpeg_turbo@295003
(8ee9bdd068effcf5fe876e401829eadb94569750)

[noel chromium, 2015-04-27 11:43:29]

Added notes to https://code.google.com/p/chromium/issues/detail?id=479758 about
the strange error/complaints from SVN enen thouhg the patch was submitted.

Closing.

[noel chromium, 2015-04-27 12:16:48]

+fdegans as an FYI.

[noel chromium, 2015-04-30 00:52:25]

Rolled into Chromium on https://codereview.chromium.org/1110113002