DERBY-2573: Make 10.8 version of builduserdocs target use ant.exec rather than ant.bat; commit derby-2573-14-aa-useAntExec.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/branches/10.8@1557223 13f79535-47bb-0310-9956-ffa450edef68