NetStandard.dll is built during the same phase as the other generated shims.
We use a ProjectReference to correctly sequence it before other generated
shims. Make sure that building a generated shim after building
netstandard.csproj doesn't result in 2 netstandard.dll's being passed to
the compiler.
Commit migrated from https://github.com/dotnet/corefx/commit/
30f4fbcb5bc16bdb3953d9186f20606a0f134f2d
<!-- reference everything but self -->
<ReferencePath
Include="$(RefPath)*.dll"
- Exclude="$(RefPath)$(MSBuildProjectName).dll" />
+ Exclude="$(RefPath)$(MSBuildProjectName).dll;$(RefPath)netstandard.dll" />
<!-- required by compiler to resolve core types -->
<ProjectReference Condition="'$(MSBuildProjectName)' != 'netstandard'"