Update year in license files

In last year's update (D48219) it was suggested that the release manager
might want to do this, so here we go.

git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@351194 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/LICENSE.txt b/LICENSE.txt
index 2183e8e..0021792 100644
--- a/LICENSE.txt
+++ b/LICENSE.txt
@@ -14,7 +14,7 @@
 University of Illinois/NCSA
 Open Source License
 
-Copyright (c) 1997-2018 Intel Corporation
+Copyright (c) 1997-2019 Intel Corporation
 
 All rights reserved.
 
@@ -51,7 +51,7 @@
 
 ==============================================================================
 
-Copyright (c) 1997-2018 Intel Corporation
+Copyright (c) 1997-2019 Intel Corporation
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal