fix wrong deleted docs count in IW's infoStream

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1596526 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5689: FieldInfo.setDocValuesGen should not be public

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/branch_4x@1596555 13f79535-47bb-0310-9956-ffa450edef68