Fix ORC TestVectorizedORCReader testcase for Timestamps

ORC vectorized tests were not testing for timestamps correctly.

java.sql.Timestamp is a confusing API, because of the mix of getTime() & getNanos() usage. Though it might look like they return independent values, getTime() includes part of the value already present in getNanos().

Please view the implementation code for the confusion

http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/6-b14/java/sql/Timestamp.java#Timestamp.getTime%28%29

Fix in HIVE-4681 caused test-failures, which needs the test to be fixed.