This property was only legitimately by the project which wants to
restore `crossgen`. Since that now comes from
Microsoft.NETCore.App (i.e. the shared framework) use
SharedFrameworkRid instead.
I also ensured that we passed UsePortableLinuxSharedFramework to
dotnet restore when restoring the tool projects, so we can use the
platform specific RID when non portable build.
* Allow host info passed in from the command line to override machine settings
* Simplify the logic
* Address PR comments to keep a separate HostRid and HostOSName that are static
* Rename to BuildInfo.props
* Address PR comments
* Fix the previous merge
* Fix spacing
* Address PR comments
