Fix a minor ABI incompatibility caused by the introduction of new error constants...

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@656 632fc199-4ca6-4c93-a231-07263d6284db

diff --cc ChangeLog.txt
index 17bf5383525e744ab39740819c446f2507ebe6c4,be51d288e4db6a16bf35e8b800b8753dfe3c50d4..1196d9b5da0b110a48996a02c97ba7cbb828b6df
--- 1/ChangeLog.txt
--- 2/ChangeLog.txt
+++ b/ChangeLog.txt
@@@ -42,6 -5,17 +42,17 @@@ the TurboJPEG compressor to grow the JP
  the application was invoked using I/O redirection
  (jpegtran <input.jpg >output.jpg).
  
 -[2] The inclusion of libjpeg v7 and v8 emulation as well as arithmetic coding
++[13] The inclusion of libjpeg v7 and v8 emulation as well as arithmetic coding
+ support in libjpeg-turbo v1.1.0 introduced several new error constants in
+ jerror.h, and these were mistakenly enabled for all emulation modes, causing
+ the error enum in libjpeg-turbo to have different values than the same enum in
+ libjpeg.  This represents an ABI incompatibility, and it caused problems with
+ applications that took specific action based on libjpeg error values.  The fix
+ was to include the new error constants conditionally based on whether libjpeg
+ v7 or v8 emulation or arithmetic coding support was enabled.  Note that to
+ achieve full ABI compatibility with jpeg-6b, it is necessary to build
+ libjpeg-turbo without arithmetic coding support.
+ 
  
  1.1.1
  =====