Add new linker files

Author: marek-safar

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Build.Tasks.csproj

@@ -340,8 +340,11 @@
     <Compile Include="$(LinkerSourceFullPath)\linker\Mono.Linker.Steps\SweepStep.cs">
       <Link>Linker\Mono.Linker.Steps\SweepStep.cs</Link>
     </Compile>
-    <Compile Include="$(LinkerSourceFullPath)\linker\Mono.Linker.Steps\MarkStep.cs">
-      <Link>Linker\Mono.Linker.Steps\MarkStep.cs</Link>
+    <Compile Include="$(LinkerSourceFullPath)\linker\Mono.Linker\LoadException.cs">
+      <Link>Linker\Mono.Linker\LoadException.cs</Link>
+    </Compile>
+    <Compile Include="$(LinkerSourceFullPath)\linker\Mono.Linker\MarkException.cs">
+      <Link>Linker\Mono.Linker\MarkException.cs</Link>
     </Compile>
     <Compile Include="Tasks\MergeResources.cs" />
     <Compile Include="Tasks\GetConvertedJavaLibraries.cs" />