OPENJPA-1631: Add synchronization to AnnotationPersistenceXMLMetaDataParser.parse() method to make it thread safe - back ported to 1.2.x Rick Curtis' trunk changes.

git-svn-id: https://svn.apache.org/repos/asf/openjpa/branches/1.2.x@1512501 13f79535-47bb-0310-9956-ffa450edef68