make test less evil

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1617928 13f79535-47bb-0310-9956-ffa450edef68
LUCENE-5884: optimize FST.ramBytesUsed

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1617940 13f79535-47bb-0310-9956-ffa450edef68