Disable buffer for subprocess pipe objects

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_3@1491012 13f79535-47bb-0310-9956-ffa450edef68
Flush subprocess stdout before trying to read from it

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_4_3@1491148 13f79535-47bb-0310-9956-ffa450edef68