More break fixes

Author: javiercn

src/Servers/Kestrel/Core/src/KestrelServerOptions.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics;
-using System.Linq;
 using System.Net;
 using System.Security.Cryptography.X509Certificates;
 using System.Text;