SOLR-5636: SolrRequestParsers does some xpath lookups on every request, which can cause concurrency issues.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1558688 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5344: adding the change to CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1558693 13f79535-47bb-0310-9956-ffa450edef68