Again... don't fail build on clean error

Author: natebeck

build/build.xml

@@ -154,7 +154,7 @@ http://bugs.adobe.com/jira/browse/SDK-20449
 
     <target name="clean" description="Delete build artifacts." depends="cleanDocs,cleanLessons">
         <delete file="${binDir}/PBEngine.swc"/>
-        <delete includeemptydirs="false" quiet="false">
+        <delete includeemptydirs="false" quiet="false" failonerror="false">
           <fileset dir="${rootDir}" includes="PushButtonEngine-*.zip"/>
           <fileset dir="${rootDir}/build/testrun/" />
         </delete>