Fix warning "warning : This project has native dependencies which were not built. [F:\workspace_work\1\s\src\SiteExtensions\Runtime\Microsoft.AspNetCore.Runtime.SiteExtension.pkgproj]"

[wtgodbe]

Part of #22240

Happens during SiteExtension build. Full warning text below:

F:\workspace_work\1\s\eng\targets\ResolveIisReferences.targets(37,5): warning : This project has native dependencies which were not built. Without this, tests may not function correctly. Run build.cmd -native to build native projects. Run build.cmd -managed -native to build both C# and C++. [F:\workspace_work\1\s\src\SiteExtensions\Runtime\Microsoft.AspNetCore.Runtime.SiteExtension.pkgproj]

[dougbu]

Fixed between builds 20200529.9 and 20200529.10 of our official pipeline. The only new commit was 14d6b6e28661 My changes in #22017 solved this one because all native assets are now created at the start of all Windows jobs on the CI.