Michael Stürmer authored Aug 29, 2017 and Brad King committed Sep 05, 2017

Since commit v3.9.0-rc4~4^2 (Vs: allow CSharp targets to be linked to
CXX targets, 2017-06-20) CSharp targets get `ProjectReference` entries
to their dependencies.  This causes VS to also reference the
dependency's output assembly by default, which is incorrect for
non-managed targets.

Fix this by setting `ReferenceOutputAssembly` to `false` for targets
that can't provide output assemblies.  Unmanaged C++ targets (shared
libs & executables) can still be referenced and a warning will be shown
in the IDE but the build will not break anymore.

Fixes: #17172