[SPARK-2814][SQL] HiveThriftServer2 throws NPE when executing native commands

JIRA issue: [SPARK-2814](https://issues.apache.org/jira/browse/SPARK-2814)

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #1753 from liancheng/spark-2814 and squashes the following commits:

c74a3b2 [Cheng Lian] Fixed SPARK-2814

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala

@@ -146,13 +146,12 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) {
   @transient protected[hive] lazy val sessionState = {
     val ss = new SessionState(hiveconf)
     set(hiveconf.getAllProperties)  // Have SQLConf pick up the initial set of HiveConf.
-    
-    ss.err = new PrintStream(outputBuffer, true, "UTF-8")
-    ss.out = new PrintStream(outputBuffer, true, "UTF-8")
-
     ss
   }
 
+  sessionState.err = new PrintStream(outputBuffer, true, "UTF-8")
+  sessionState.out = new PrintStream(outputBuffer, true, "UTF-8")
+
   override def set(key: String, value: String): Unit = {
     super.set(key, value)
     runSqlHive(s"SET $key=$value")