Update CHANGES.txt for commit of MR-6549 to branch-2.7 and branch-2.6.

(cherry picked from commit 43acf9ab8ef4eea7950fa99096cd99459cfa25ad)

hadoop-mapreduce-project/CHANGES.txt

@@ -394,6 +394,9 @@ Release 2.7.3 - UNRELEASED
     MAPREDUCE-5883. "Total megabyte-seconds" in job counters is slightly
     misleading (Nathan Roberts via jlowe)
 
+    MAPREDUCE-6549. multibyte delimiters with LineRecordReader cause
+    duplicate records (wilfreds via rkanter)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES
@@ -699,6 +702,9 @@ Release 2.6.3 - UNRELEASED
     MAPREDUCE-5883. "Total megabyte-seconds" in job counters is slightly
     misleading (Nathan Roberts via jlowe)
 
+    MAPREDUCE-6549. multibyte delimiters with LineRecordReader cause
+    duplicate records (wilfreds via rkanter)
+
 Release 2.6.2 - 2015-10-28
 
   INCOMPATIBLE CHANGES