Use Directory.Build.targets/props

Directory.Build.props

@@ -1,12 +1,12 @@
-<Project>
-  <Import Project="dependencies.props" />
-  <Import Project="..\version.xml" />
+<Project>
+  <Import Project="build/dependencies.props" />
+  <Import Project="version.xml" />
 
   <PropertyGroup>
     <Product>Microsoft ASP.NET Core</Product>
     <RepositoryUrl>https://github.com/aspnet/Antiforgery</RepositoryUrl>
     <RepositoryType>git</RepositoryType>
-    <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)Key.snk</AssemblyOriginatorKeyFile>
+    <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)build\Key.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>
     <PublicSign Condition="'$(OS)' != 'Windows_NT'">true</PublicSign>
     <VersionSuffix Condition="'$(VersionSuffix)'!='' AND '$(BuildNumber)' != ''">$(VersionSuffix)-$(BuildNumber)</VersionSuffix>

Directory.Build.targets

@@ -0,0 +1,2 @@
+<Project>
+</Project>

src/Microsoft.AspNetCore.Antiforgery/Microsoft.AspNetCore.Antiforgery.csproj

@@ -1,7 +1,5 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-  <Import Project="..\..\build\common.props" />
-
   <PropertyGroup>
     <Description>An antiforgery system for ASP.NET Core designed to generate and validate tokens to prevent Cross-Site Request Forgery attacks.</Description>
     <TargetFramework>netstandard2.0</TargetFramework>

test/Microsoft.AspNetCore.Antiforgery.Test/Microsoft.AspNetCore.Antiforgery.Test.csproj

@@ -1,6 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <Import Project="..\..\build\common.props" />
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFrameworks>netcoreapp2.0;net461</TargetFrameworks>