HADOOP-12081. Fix UserGroupInformation.java to support 64-bit zLinux. (aajisaka)

(cherry picked from commit 773c670943757681feeafb227a2d0c29d48f38f1)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -202,6 +202,9 @@ Release 2.8.0 - UNRELEASED
     HADOOP-11893. Mark org.apache.hadoop.security.token.Token as
     @InterfaceAudience.Public. (Brahma Reddy Battula via stevel)
 
+    HADOOP-12081. Fix UserGroupInformation.java to support 64-bit zLinux.
+    (aajisaka)
+
   OPTIMIZATIONS
 
     HADOOP-11785. Reduce the number of listStatus operation in distcp

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java

@@ -357,7 +357,8 @@ public class UserGroupInformation {
   private static final boolean windows =
       System.getProperty("os.name").startsWith("Windows");
   private static final boolean is64Bit =
-      System.getProperty("os.arch").contains("64");
+      System.getProperty("os.arch").contains("64") ||
+      System.getProperty("os.arch").contains("s390x");
   private static final boolean aix = System.getProperty("os.name").equals("AIX");
 
   /* Return the OS login module class name */