add comment on duplicated functionality

Author: JackBuggins

hadoop-common-project/hadoop-minikdc/src/test/java/org/apache/hadoop/minikdc/TestMiniKdc.java

@@ -39,7 +39,7 @@
 
 public class TestMiniKdc extends KerberosSecurityTestcase {
   private static final boolean IBM_JAVA = shouldUseIbmPackages();
-
+  // duplicated to avoid cycles in the build
   private static boolean shouldUseIbmPackages() {
     if (System.getProperty("java.vendor").contains("IBM")) {
       try {