Remove extra semicolon in Task.scala

Author: GuoQiang Li <witgo@qq.com>

Closes #1876 from witgo/remove_semicolon_in_Task_scala and squashes the following commits:

c6ea732 [GuoQiang Li] Remove extra semicolon in Task.scala

core/src/main/scala/org/apache/spark/scheduler/Task.scala

@@ -46,7 +46,7 @@ private[spark] abstract class Task[T](val stageId: Int, var partitionId: Int) ex
 
   final def run(attemptId: Long): T = {
     context = new TaskContext(stageId, partitionId, attemptId, runningLocally = false)
-    context.taskMetrics.hostname = Utils.localHostName();
+    context.taskMetrics.hostname = Utils.localHostName()
     taskThread = Thread.currentThread()
     if (_killed) {
       kill(interruptThread = false)