Merged revision(s) 1624924 from lucene/dev/trunk:
Don't use a SimpleFSLockFactory for RAMDirectoryFactory in Solr (fails tests in trunk)

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1624925 13f79535-47bb-0310-9956-ffa450edef68