Add compatibility with IsTool and GeneratePackageOnBuild from SDK Pack

Fixes NuGet/Home#5104

Author: kzu

src/Build/NuGet.Build.Packaging.Tasks/NuGet.Build.Packaging.Compatibility.targets

@@ -0,0 +1,19 @@
+<!--
+***********************************************************************************************
+Microsoft.NuGet.Build.Packaging.Compatibility.targets
+
+WARNING:  DO NOT MODIFY this file unless you are knowledgeable about MSBuild and have
+          created a backup copy.  Incorrect changes to this file will make it
+          impossible to load or build your projects from the command-line or the IDE.
+
+Copyright (c) .NET Foundation. All rights reserved. 
+***********************************************************************************************
+-->
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+
+	<PropertyGroup>
+		<PackOnBuild Condition="'$(GeneratePackageOnBuild)' == 'true'">true</PackOnBuild>
+		<PrimaryOutputPackageFileKind Condition="'$(IsTool)' == 'true'">tool</PrimaryOutputPackageFileKind>
+	</PropertyGroup>
+
+</Project>

src/Build/NuGet.Build.Packaging.Tasks/NuGet.Build.Packaging.Tasks.csproj

@@ -8,25 +8,27 @@
     <OutputType>Exe</OutputType>
     <TargetExt>.dll</TargetExt>
     <StartupObject>NuGet.Build.Packaging.Program</StartupObject>
+    <PackOnBuild Condition="'$(PackOnBuild)' == '' And '$(Configuration)' == 'Release'">true</PackOnBuild>
+	  <PackageOutputPath Condition="'$(PackageOutputPath)' == ''">..\..\..\out</PackageOutputPath>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
     <Reference Include="System.Core" />
   </ItemGroup>
-	<ItemGroup>
-		<PackageReference Include="Costura.Fody" Version="1.3.3" />
-		<PackageReference Include="Fody" Version="1.29.4" />
-		<PackageReference Include="GitInfo" Version="1.*" />
- 		<PackageReference Include="netfx-System.StringResources" Version="*" />
-		<PackageReference Include="Microsoft.Build" Version="14.3.0" />
-		<PackageReference Include="Microsoft.Build.Tasks.Core" Version="14.3.0" />
-		<PackageReference Include="MSBuilder.ThisAssembly.Project" Version="0.3.3" />
-		<PackageReference Include="Newtonsoft.Json" Version="6.0.8" />
-		<PackageReference Include="NuGet.Client" Version="4.0.0" />
-		<PackageReference Include="NuGet.Packaging" Version="4.0.0" />
-		<PackageReference Include="NuGet.ProjectManagement" Version="4.0.0" />
-	</ItemGroup>
-	<ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Costura.Fody" Version="1.3.3" PrivateAssets="all" />
+    <PackageReference Include="Fody" Version="1.29.4" PrivateAssets="all" />
+    <PackageReference Include="GitInfo" Version="1.*" PrivateAssets="all" />
+    <PackageReference Include="netfx-System.StringResources" Version="*" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.Build" Version="14.3.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.Build.Tasks.Core" Version="14.3.0" PrivateAssets="all" />
+    <PackageReference Include="MSBuilder.ThisAssembly.Project" Version="0.3.3" PrivateAssets="all" />
+    <PackageReference Include="Newtonsoft.Json" Version="6.0.8" PrivateAssets="all" />
+    <PackageReference Include="NuGet.Client" Version="4.0.0" PrivateAssets="all" />
+    <PackageReference Include="NuGet.Packaging" Version="4.0.0" PrivateAssets="all" />
+    <PackageReference Include="NuGet.ProjectManagement" Version="4.0.0" PrivateAssets="all" />
+  </ItemGroup>
+  <ItemGroup>
     <Content Include="FodyWeavers.xml" />
     <Content Include="NuGet.Build.Packaging.props">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
@@ -47,6 +49,9 @@
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       <SubType>Designer</SubType>
     </Content>
+    <Content Include="NuGet.Build.Packaging.Compatibility.targets">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <None Include="NuGet.Build.Packaging.Version.props">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>

src/Build/NuGet.Build.Packaging.Tasks/NuGet.Build.Packaging.targets

@@ -19,6 +19,8 @@ Copyright (c) .NET Foundation. All rights reserved.
 	<UsingTask TaskName="NuGet.Build.Packaging.Tasks.GetApiIntersectTargetPaths" AssemblyFile="NuGet.Build.Packaging.Tasks.dll" />
 
 	<Import Project="NuGet.Build.Packaging.props" Condition="'$(NuGetBuildPackagingPropsImported)' == ''" />
+	<!-- Adds compatibility targets with Pack SDK -->
+	<Import Project="NuGet.Build.Packaging.Compatibility.targets" />
 
 	<PropertyGroup>
 		<!-- The Kind of primary output (build, symbols and doc) set if IncludeOutputsInPackage = true -->
@@ -215,7 +217,7 @@ Copyright (c) .NET Foundation. All rights reserved.
 		</InferPackageContentsDependsOn>
 		<GetPackageContentsDependsOn>InferPackageContents</GetPackageContentsDependsOn>
 	</PropertyGroup>
-	
+
 	<Target Name="GetPackageContents" DependsOnTargets="$(GetPackageContentsDependsOn)" Returns="@(_PackageContent)">
 		<!-- We batch depending on the IsPackaging metadata, which is only specified for referenced content 
 			 if the current project is building a package, to force retargeting of the referenced content. -->