HIVE-4724 Better detection of non-ORC files in the ORC reader (omalley)


git-svn-id: https://svn.apache.org/repos/asf/hive/trunk@1505187 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HIVE-4779-trunk-gd