Work around sdk 1.1 compat bug

Recent builds of the SDK introduced a bug around referencing netstandard
1.6 projects. This trigged on several Roslyn projects and cause build
breaks with newer builds of VS.

Suppressing the check for now. Will undo when we move to 2.0 SDK

https://github.com/dotnet/roslyn/issues/21183

build/Targets/Settings.props

@@ -75,6 +75,9 @@
       {RawFileName};
     </AssemblySearchPaths>
 
+    <!-- https://github.com/dotnet/roslyn/issues/21183 -->
+    <ImplicitlyExpandNETStandardFacades>false</ImplicitlyExpandNETStandardFacades>
+
     <RoslynNetSdkRootPath>$(MSBuildSDKsPath)\Microsoft.NET.Sdk\Sdk\</RoslynNetSdkRootPath> 
     <RestoreProjectStyle>PackageReference</RestoreProjectStyle>