OAK-2021 XPath queries with certain combinations of "or" conditions don't use an index
OAK-2022 XPath queries with "order by" are never converted to "union"

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1617430 13f79535-47bb-0310-9956-ffa450edef68