fixed some unit tests

Author: arturcic

src/GitVersionTask.MsBuild/LibGit2Sharp/GitLoaderContext.cs

@@ -2,7 +2,6 @@
 #if !NETFRAMEWORK
 using System;
 using System.IO;
-using System.Linq;
 using System.Reflection;
 using System.Runtime.InteropServices;
 using System.Runtime.Loader;