add api diff for avalonia.base

Avalonia.sln

@@ -150,6 +150,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Props", "Props", "{F3AC8BC1
 		build\System.Memory.props = build\System.Memory.props
 		build\UnitTests.NetFX.props = build\UnitTests.NetFX.props
 		build\XUnit.props = build\XUnit.props
+		build\ApiDiff.props = build\ApiDiff.props
 	EndProjectSection
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Targets", "Targets", "{4D6FAF79-58B4-482F-9122-0668C346364C}"

build/ApiDiff.props

@@ -0,0 +1,7 @@
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <PackageDownload Include="Avalonia" Version="[0.10.0-preview1]" />
+    <PackageReference Include="Microsoft.DotNet.ApiCompat" Version="5.0.0-beta.20364.3" PrivateAssets="All" />
+    <ResolvedMatchingContract Include="$(NuGetPackageRoot)\avalonia\0.10.0-preview1\lib\netstandard2.0\$(AssemblyName).dll" />
+  </ItemGroup>
+</Project>

build/Base.props

@@ -2,7 +2,5 @@
   <ItemGroup>
     <PackageReference Include="System.ValueTuple" Version="4.5.0" />
     <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="4.6.0" />
-    <PackageReference Include="Microsoft.DotNet.ApiCompat" Version="5.0.0-beta.20364.3" PrivateAssets="All" />
-    <ResolvedMatchingContract Include="$(NuGetPackageRoot)\avalonia\0.10.0-preview1\lib\netstandard2.0\$(AssemblyName).dll" />
   </ItemGroup>
 </Project>

src/Avalonia.Base/Avalonia.Base.csproj

@@ -13,4 +13,5 @@
   <Import Project="..\..\build\Rx.props" />
   <Import Project="..\..\build\JetBrains.Annotations.props" />
   <Import Project="..\..\build\System.Memory.props" />
+  <Import Project="..\..\build\ApiDiff.props" />
 </Project>