Automated build revealed problems in _Image_JPEG due to redefinition of size_t: http://bugs.debian.org/750430
The commit log message (8b7ca6ff970aed0c) for the "#define size_t unsigned int" line talks about applying kludges from image_jpeg.c. The commit log message from image_jpeg.c is from 1998 and reads "header file compat fixes (what happened?)", but the change was undone there in 2008 by 4e36f92cfa282f0b, and so you should probably restore transupp.c as well.
