[EXAMPLE][MINOR] Add missing awaitTermination in click stream example

Author: jerryshao <sshao@hortonworks.com>

Closes #9730 from jerryshao/clickstream-fix.

examples/src/main/scala/org/apache/spark/examples/streaming/clickstream/PageViewStream.scala

@@ -18,7 +18,6 @@
 // scalastyle:off println
 package org.apache.spark.examples.streaming.clickstream
 
-import org.apache.spark.SparkContext._
 import org.apache.spark.streaming.{Seconds, StreamingContext}
 import org.apache.spark.examples.streaming.StreamingExamples
 // scalastyle:off
@@ -88,7 +87,7 @@ object PageViewStream {
 
     // An external dataset we want to join to this stream
     val userList = ssc.sparkContext.parallelize(
-       Map(1 -> "Patrick Wendell", 2->"Reynold Xin", 3->"Matei Zaharia").toSeq)
+       Map(1 -> "Patrick Wendell", 2 -> "Reynold Xin", 3 -> "Matei Zaharia").toSeq)
 
     metric match {
       case "pageCounts" => pageCounts.print()
@@ -106,6 +105,7 @@ object PageViewStream {
     }
 
     ssc.start()
+    ssc.awaitTermination()
   }
 }
 // scalastyle:on println