Fix for jira#1533 (default attributes in the definition for an element that is...

Fix for jira#1533 (default attributes in the definition for an element that is not validated because of errors would be added to the list of attributes even if already present)

git-svn-id: https://svn.apache.org/repos/asf/xerces/c/trunk@359082 13f79535-47bb-0310-9956-ffa450edef68