8237210: Modify the header to include Oracle copyright line

Reviewed-by: jjg
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeDiffer.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeDiffer.java
index c278ff9..124fa61 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeDiffer.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeDiffer.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018, Google LLC. All rights reserved.
+ * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
diff --git a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeHasher.java b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeHasher.java
index 3b85e11..22e49a9 100644
--- a/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeHasher.java
+++ b/src/jdk.compiler/share/classes/com/sun/tools/javac/comp/TreeHasher.java
@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2018, Google LLC. All rights reserved.
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it