Update CHANGES.txt for TEZ-3235.
Update CHANGES.txt for TEZ-3235.

ueshin/apache-tez,apache/tez,apache/tez,sidseth/tez,sidseth/tez,apache/tez,ueshin/apache-tez,ChetnaChaudhari/tez,ueshin/apache-tez,apache/tez,ChetnaChaudhari/tez,ueshin/apache-tez,sidseth/tez,ueshin/apache-tez,sidseth/tez,ChetnaChaudhari/tez,sidseth/tez,ChetnaChaudhari/tez,ChetnaChaudhari/tez,apache/tez