SOLR-5760: ConcurrentUpdateSolrServer has a blockUntilFinished call when streamDeletes is true that should be tucked into the if statement below it. (merged branch_4x r1573441)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_7@1581168 13f79535-47bb-0310-9956-ffa450edef68