Fix waitForMerges to allow merge schedule to run one last time

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1618667 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6387: Add better error messages throughout Solr and supply a work around for Java bug #8047340 to SystemInfoHandler: On Turkish default locale, some JVMs fail to fork on MacOSX, BSD, AIX, and Solaris platforms.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1618672 13f79535-47bb-0310-9956-ffa450edef68