Upgrade to Xerces 2.12

[ebruchez]

+1 from customer

[ebruchez]

We must also patch Xerces 2.12. See #3444 and https://github.com/orbeon/xerces2-j/commits/Xerces-J_2_11_0-orbeon.

[ebruchez]

Getting the new branch:

git clone https://github.com/orbeon/xerces2-j.git xerces2-j-orbeon
cd xerces2-j-orbeon
git remote add apache-xerces2-j https://github.com/apache/xerces2-j.git
git fetch --tags apache-xerces2-j
git co -b Xerces-J_2_12_0-orbeon Xerces-J_2_12_0
git push --set-upstream origin Xerces-J_2_12_0-orbeon

[ebruchez]

Cherry-picked our 3 commits here.

Building:

setjdk 1.8
ant -Djavac.source=1.6 -Djavac.target=1.6 jar
cp  build/xercesImpl.jar ~/Orbeon/OF/lib/src/xerces-xercesImpl-2.12.jar
cd ~/Orbeon/OF
ant jarjar
cp lib/xerces-2.12-orbeon.jar lib/runtime/xerces-2.12-orbeon.jar