Add net451 back and use msbuild directly

Author: kjnilsson

build.bat

@@ -1,5 +1,5 @@
 @ECHO OFF
 dotnet restore
 dotnet run -p .\projects\client\Apigen --apiName:AMQP_0_9_1 .\docs\specs\amqp0-9-1.stripped.xml .\gensrc\autogenerated-api-0-9-1.cs
-dotnet build .\projects\client\RabbitMQ.Client
+msbuild.\projects\client\RabbitMQ.Client
 dotnet build .\projects\client\Unit

build.sh

@@ -7,5 +7,6 @@ SCRIPT_DIR=$(cd $(dirname "$SCRIPT") && pwd)
 
 dotnet restore ./RabbitMQDotNetClient.sln
 dotnet run -p $SCRIPT_DIR/projects/client/Apigen/Apigen.csproj --apiName:AMQP_0_9_1 $SCRIPT_DIR/docs/specs/amqp0-9-1.stripped.xml $SCRIPT_DIR/gensrc/autogenerated-api-0-9-1.cs
-dotnet build $SCRIPT_DIR/projects/client/RabbitMQ.Client/RabbitMQ.Client.csproj
+# we have to use msbuild or else multi-targeting doesn't work
+msbuild $SCRIPT_DIR/projects/client/RabbitMQ.Client/RabbitMQ.Client.csproj
 dotnet build $SCRIPT_DIR/projects/client/Unit/Unit.csproj

projects/client/RabbitMQ.Client/RabbitMQ.Client.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <Description>The RabbitMQ .NET client is the official client library for C# (and, implicitly, other .NET languages)</Description>
     <VersionPrefix>5.3.2</VersionPrefix>
-    <TargetFrameworks>netstandard1.5</TargetFrameworks>
+    <TargetFrameworks>net451;netstandard1.5</TargetFrameworks>
     <NoWarn>$(NoWarn);CS1591</NoWarn>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
@@ -28,6 +28,12 @@
     <Compile Include="..\..\..\gensrc\autogenerated-api-0-9-1.cs" Exclude="build\**\*;bin\**;obj\**;**\*.xproj;packages\**" />
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net451' ">
+    <PackageReference Include="Microsoft.Diagnostics.Tracing.EventSource.Redist" Version="1.1.*" />
+    <Reference Include="System" />
+    <Reference Include="Microsoft.CSharp" />
+  </ItemGroup>
+
   <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard1.5' ">
     <DefineConstants>$(DefineConstants);CORECLR</DefineConstants>
   </PropertyGroup>