Merge pull request #20859 from jtattermusch/fix_20782

C#: fix #20782

src/csharp/Grpc.Core/build/net45/Grpc.Core.targets

@@ -2,32 +2,32 @@
 <Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\win\native\grpc_csharp_ext.x86.dll">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
       <Link>grpc_csharp_ext.x86.dll</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\win\native\grpc_csharp_ext.x64.dll">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
       <Link>grpc_csharp_ext.x64.dll</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux\native\libgrpc_csharp_ext.x86.so">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x86.so</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux\native\libgrpc_csharp_ext.x64.so">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x64.so</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\osx\native\libgrpc_csharp_ext.x86.dylib">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x86.dylib</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\osx\native\libgrpc_csharp_ext.x64.dylib">
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x64.dylib</Link>
       <Visible>false</Visible>
     </Content>