Even if the XSTS suite thinks differently, the XMLSchema 1.1 clarifies that...

Even if the XSTS suite thinks differently, the XMLSchema 1.1 clarifies that two values derived from the same value space should be treated as equals; so find out the common ancestor and use it to perform the comparison

git-svn-id: https://svn.apache.org/repos/asf/xerces/c/trunk@504487 13f79535-47bb-0310-9956-ffa450edef68