[SPARK-21783][SQL] Turn on ORC filter push-down by default

Author: dongjoon-hyun

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -325,7 +325,7 @@ object SQLConf {
   val ORC_FILTER_PUSHDOWN_ENABLED = buildConf("spark.sql.orc.filterPushdown")
     .doc("When true, enable filter pushdown for ORC files.")
     .booleanConf
-    .createWithDefault(false)
+    .createWithDefault(true)
 
   val HIVE_VERIFY_PARTITION_PATH = buildConf("spark.sql.hive.verifyPartitionPath")
     .doc("When true, check all the partition paths under the table\'s root directory " +