use FileUtils in a static way - submitted by Kevin Jackson

git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@328709 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/Concat.java

@@ -571,7 +571,7 @@ public class Concat extends Task {
             throw new BuildException("Error while concatenating: "
                                      + ioex.getMessage(), ioex);
         } finally {
-            FILE_UTILS.close(os);
+            FileUtils.close(os);
         }
     }