Add missing license headers to .cs files

There are 77 .cs files in the repo lacking the standard license header we have on the other ~5400 .cs files.  This commit adds the missing ones.

Author: stephentoub

src/Common/src/Interop/Windows/mincore/Interop.DuplicateHandle.cs

@@ -1,3 +1,6 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
 using Microsoft.Win32.SafeHandles;
 using System;
 using System.Runtime.InteropServices;

src/Microsoft.CSharp/src/Resources/Strings.Designer.cs

@@ -1,3 +1,6 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
 using System;
 using System.Runtime.InteropServices;
 using Microsoft.Win32.SafeHandles;

src/Microsoft.Win32.Registry/tests/Helpers.cs

@@ -1,4 +1,7 @@
-using Xunit;
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Xunit;
 
 namespace System.ComponentModel.DataAnnotations
 {

src/System.ComponentModel.Annotations/tests/EditableAttributeTests.cs

@@ -1,4 +1,7 @@
-using Xunit;
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Xunit;
 
 namespace System.ComponentModel.DataAnnotations
 {

src/System.ComponentModel.Annotations/tests/ScaffoldColumnAttributeTests.cs

@@ -1,4 +1,7 @@
-using System;
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
 
 using Xunit;
 

src/System.Diagnostics.Debug/tests/AttributeTests.cs

@@ -1,3 +1,6 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
 using System;
 using System.Security;
 

src/System.Diagnostics.Process/src/System/Diagnostics/ProcessStartInfo.Unix.cs

@@ -1,3 +1,6 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
 using System.Security;
 
 namespace System.Diagnostics

src/System.Diagnostics.Process/src/System/Diagnostics/ProcessStartInfo.Windows.cs

@@ -1,4 +1,7 @@
-using System.IO.Pipes;
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.IO.Pipes;
 using System.Threading.Tasks;
 
 namespace System.Diagnostics.ProcessTests

src/System.Diagnostics.Process/tests/System.Diagnostics.Process.TestConsoleApp/TestConsoleApp.cs

@@ -1,4 +1,7 @@
-using System;
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
 using System.Collections.Generic;
 using System.Text;
 using System.Threading;