Fix addition of CPU features when running against legacy libvirt

When running against an libvirt < 0.9.10 which lacks support for the
'host-model' CPU type, we must fake it by copying the host CPU
model and features. Unfortunately the code was forgetting to
append the new features to the CPU object feature list

Bug: 1099527
Change-Id: I39c6df6e85d77763ad279961fd6f0da70ac2415e
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Merge "Fix addition of CPU features when running against legacy libvirt"