Merge pull request #23391 from Emeka-NMC/master

Fix incremental build of csproj projects depending on grpc.

src/csharp/Grpc.Core/build/MonoAndroid10/Grpc.Core.targets

@@ -3,21 +3,21 @@
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == 'MonoAndroid'">
     <AndroidNativeLibrary Include="$(MSBuildThisFileDirectory)..\..\native\android\arm64-v8a\libgrpc_csharp_ext.so">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Abi>arm64-v8a</Abi>
     </AndroidNativeLibrary>
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == 'MonoAndroid'">
     <AndroidNativeLibrary Include="$(MSBuildThisFileDirectory)..\..\native\android\armeabi-v7a\libgrpc_csharp_ext.so">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Abi>armeabi-v7a</Abi>
     </AndroidNativeLibrary>
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' == 'MonoAndroid'">
     <AndroidNativeLibrary Include="$(MSBuildThisFileDirectory)..\..\native\android\x86\libgrpc_csharp_ext.so">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Abi>x86</Abi>
     </AndroidNativeLibrary>
   </ItemGroup>

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

@@ -11,32 +11,32 @@
   -->
   <ItemGroup Condition="'$(Grpc_SkipNativeLibsCopy)' != 'true'">
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\win\native\grpc_csharp_ext.x86.dll">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>grpc_csharp_ext.x86.dll</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\win\native\grpc_csharp_ext.x64.dll">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>grpc_csharp_ext.x64.dll</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux\native\libgrpc_csharp_ext.x86.so">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x86.so</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\linux\native\libgrpc_csharp_ext.x64.so">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x64.so</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\osx\native\libgrpc_csharp_ext.x86.dylib">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x86.dylib</Link>
       <Visible>false</Visible>
     </Content>
     <Content Include="$(MSBuildThisFileDirectory)..\..\runtimes\osx\native\libgrpc_csharp_ext.x64.dylib">
-      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <Link>libgrpc_csharp_ext.x64.dylib</Link>
       <Visible>false</Visible>
     </Content>