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
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
(cherry picked from commit 82b55c97d10a55e6a825261397816f6a7ad00fd7)

Change-Id: Ib5e6a173f1ae7d421435af45bf327f5b36c94dd0
Merge "Fix addition of CPU features when running against legacy libvirt" into stable/folsom