HDFS-4046. Merge the CHANGES.txt change from trunk revision 1406019

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1406020 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -106,6 +106,9 @@ Release 2.0.3-alpha - Unreleased
     HDFS-4143. Change blocks to private in INodeFile and renames isLink() to
     isSymlink() in INode. (szetszwo)
 
+    HDFS-4046. Rename ChecksumTypeProto enum NULL since it is illegal in
+    C/C++. (Binglin Chang via suresh)
+
   OPTIMIZATIONS
 
   BUG FIXES