[CODEC-174] Small (4-5%) but consistent performance gain with this patch from https://issues.apache.org/jira/secure/attachment/12613346/CODEC-174-refactor-join-method-in-Phoneme.patch

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/codec/trunk@1541234 13f79535-47bb-0310-9956-ffa450edef68