[SYCL][NFC] Update copyright header in handler files (#1271)

Also update year in LICENSE.TXT.

Signed-off-by: Alexey Bader <[email protected]>

Author: bader

sycl/LICENSE.TXT

@@ -239,7 +239,7 @@ Legacy LLVM License (https://llvm.org/docs/DeveloperPolicy.html#legacy):
 University of Illinois/NCSA
 Open Source License
 
-Copyright (c) 2003-2019 University of Illinois at Urbana-Champaign.
+Copyright (c) 2003-2020 University of Illinois at Urbana-Champaign.
 All rights reserved.
 
 Developed by:

sycl/include/CL/sycl/handler.hpp

@@ -1,12 +1,10 @@
-//==-------- handler.hpp --- SYCL command group handler --------*- C++ -*---==//
+//==-------- handler.hpp --- SYCL command group handler --------------------==//
 //
-// Copyright (C) 2018 Intel Corporation. All rights reserved.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// The information and source code contained herein is the exclusive property
-// of Intel Corporation and may not be disclosed, examined or reproduced in
-// whole or in part without explicit written authorization from the company.
-//
-// ===--------------------------------------------------------------------=== //
+//===----------------------------------------------------------------------===//
 
 #pragma once
 

sycl/source/handler.cpp

@@ -1,12 +1,10 @@
-//==-------- handler.cpp --- SYCL command group handler --------*- C++ -*---==//
+//==-------- handler.cpp --- SYCL command group handler --------------------==//
 //
-// Copyright (C) 2019 Intel Corporation. All rights reserved.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// The information and source code contained herein is the exclusive property
-// of Intel Corporation and may not be disclosed, examined or reproduced in
-// whole or in part without explicit written authorization from the company.
-//
-// ===--------------------------------------------------------------------=== //
+//===----------------------------------------------------------------------===//
 
 #include <CL/sycl/detail/common.hpp>
 #include <CL/sycl/detail/helpers.hpp>