Try to workaround/ignore kept open files of JaCoCo ant task

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1846945 13f79535-47bb-0310-9956-ffa450edef68

src/integrationtest/build.xml

@@ -82,7 +82,9 @@ Before running this, you should execute the "assemble" target in the main build.
 
     <target name="runCompileTest" depends="init" description="Verify that we can compile most examples without including excelant or scratchpad jars">
         <!-- clean out old stuff in build-dir -->
-        <delete dir="${build}"/>
+        <delete dir="${build}" quiet="true" failonerror="false"/>
+        <!-- ... try again - on Windows, the JaCoCo ant task seems to keep files open and hence the lib directory can't be removed -->
+        <delete dir="${build}" quiet="true" failonerror="false"/>
         <mkdir dir="${build}"/>
 
         <!-- select latest built jar files without scratchpad.jar -->