FOP-2415: prevent NPE when Indic script syllabizer is not available

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1630279 13f79535-47bb-0310-9956-ffa450edef68
FOP-2157: Deadlock in CompareUtil class; patch by Jacopo Cappellato based on original proposal by Morten Knudsen.

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1630586 13f79535-47bb-0310-9956-ffa450edef68