Add a new line in the end of JobCancellationSuite.scala.

Author: rxin

core/src/test/scala/org/apache/spark/JobCancellationSuite.scala

@@ -240,4 +240,4 @@ class JobCancellationSuite extends FunSuite with ShouldMatchers with BeforeAndAf
 object JobCancellationSuite {
   val taskStartedSemaphore = new Semaphore(0)
   val taskCancelledSemaphore = new Semaphore(0)
-}
+}