Have Checkstyle fail the build if there are any warnings

git-svn-id: https://svn.apache.org/repos/asf/xmlgraphics/fop/trunk@1551637 13f79535-47bb-0310-9956-ffa450edef68

build.xml

@@ -1062,7 +1062,7 @@ NOTE:
   <target name="checkstyle" depends="package, checkstyle-avail" if="checkstyle.avail" description="Runs Checkstyle for a code quality report">
     <taskdef name="checkstyle" classname="com.puppycrawl.tools.checkstyle.CheckStyleTask" classpathref="checkstyle-classpath"/>
     <mkdir dir="${build.dir}"/>
-    <checkstyle config="${checkstyle.config}" failonviolation="false">
+    <checkstyle config="${checkstyle.config}" failonviolation="true" maxWarnings="0">
       <classpath>
         <path refid="checkstyle-classpath"/>
         <pathelement location="${build.classes.dir}"/>