SOLR-4489: fix StringIndexOutOfBoundsException in SpellCheckComponent

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1507042 13f79535-47bb-0310-9956-ffa450edef68
merge trunk

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/branches/lucene5127@1507180 13f79535-47bb-0310-9956-ffa450edef68