Add msbuild targets to C# tools for protoc compilers (#4648)

* Added props to C# tools

* Add targets file to makefile.am

Makefile.am

@@ -51,6 +51,7 @@ pkgconfig_DATA = protobuf.pc protobuf-lite.pc
 csharp_EXTRA_DIST=                                                           \
   csharp/.gitignore                                                          \
   csharp/CHANGES.txt                                                         \
+  csharp/Google.Protobuf.Tools.targets                                       \
   csharp/Google.Protobuf.Tools.nuspec                                        \
   csharp/README.md                                                           \
   csharp/build_packages.bat                                                  \

csharp/Google.Protobuf.Tools.nuspec

@@ -33,5 +33,7 @@
     <file src="..\src\google\protobuf\timestamp.proto" target="tools\google\protobuf" />
     <file src="..\src\google\protobuf\type.proto" target="tools\google\protobuf" />
     <file src="..\src\google\protobuf\wrappers.proto" target="tools\google\protobuf" />
+    <file src="Google.Protobuf.Tools.targets" target="buildCrossTargeting" />
+    <file src="Google.Protobuf.Tools.targets" target="build" />
   </files>
 </package>

csharp/Google.Protobuf.Tools.targets

+<Project>
+    <PropertyGroup>
+        <protoc_linux64>$(MSBuildThisFileDirectory)..\tools\linux_x64\protoc</protoc_linux64>
+        <protoc_linux86>$(MSBuildThisFileDirectory)..\tools\linux_x86\protoc</protoc_linux86>
+        <protoc_macosx64>$(MSBuildThisFileDirectory)..\tools\macosx_x64\protoc</protoc_macosx64>
+        <protoc_macosx86>$(MSBuildThisFileDirectory)..\tools\macosx_x86\protoc</protoc_macosx86>
+        <protoc_windows64>$(MSBuildThisFileDirectory)..\tools\windows_x64\protoc.exe</protoc_windows64>
+        <protoc_windows86>$(MSBuildThisFileDirectory)..\tools\windows_x86\protoc.exe</protoc_windows86>
+        <protoc Condition="'$([MSBuild]::IsOsPlatform(Linux))' And '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)'=='X64'">$(protoc_linux64)</protoc>
+        <protoc Condition="'$([MSBuild]::IsOsPlatform(Linux))' And '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)'=='X86'">$(protoc_linux86)</protoc>
+        <protoc Condition="'$([MSBuild]::IsOsPlatform(OSX))' And '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)'=='X64'">$(protoc_macosx64)</protoc>
+        <protoc Condition="'$([MSBuild]::IsOsPlatform(OSX))' And '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)'=='X86'">$(protoc_macosx86)</protoc>
+        <protoc Condition="'$([MSBuild]::IsOsPlatform(Windows))' And '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)'=='X64'">$(protoc_windows64)</protoc>
+        <protoc Condition="'$([MSBuild]::IsOsPlatform(Windows))' And '$([System.Runtime.InteropServices.RuntimeInformation]::OSArchitecture)'=='X86'">$(protoc_windows86)</protoc>
+    </PropertyGroup>
+</Project>
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