with it a vareity of bug fixes, both security and behavior. See
http://www.libexpat.org/ for the list.
NOTE: I already backported the expat hash randomization fix in March.
Fixes issue #14340.
The problem was that pyconfig.h was being included before some system headers
which caused redefinitions and other breakage. This moves system headers
after expat_config.h which includes pyconfig.h.