Disable ngen for the BuildHost

Trying to ngen this produces some errors because we're not shipping
the dependencies that are used for the console-application portion of it
(like parsing command line switches and locating an MSBuild in that
process). But we don't have any need for that, so we can just disable
ngen to silence errors.

src/VisualStudio/Setup/Roslyn.VisualStudio.Setup.csproj

@@ -184,6 +184,10 @@
       <ForceIncludeInVSIX>true</ForceIncludeInVSIX>
       <AdditionalProperties>TargetFramework=net472</AdditionalProperties>
       <PkgDefEntry>BindingRedirect</PkgDefEntry>
+      <!-- Don't ngen the BuildHost executable. We don't expect it to be used in Visual Studio scenarios, except for third-party extensions that might be using it.
+           At the moment, it's consumed not as a running executable but rather as a library, and it also has some dependencies for the executable portion, like
+           command line parsing and MSBuildLocator that we don't expect to be shipping either. -->
+      <Ngen>false</Ngen>
     </ProjectReference>
     <ProjectReference Include="..\..\Workspaces\CSharp\Portable\Microsoft.CodeAnalysis.CSharp.Workspaces.csproj">
       <Name>CSharpWorkspace</Name>