Force the installation of qemu packages

When doing upgrades after adding a new apt channel (like UCA),
the apt module will upgrade the directly listed packages, and its
recommended packages, not the child dependencies.

You could arrive to a state where qemu-system-x86 was installed
but not upgraded, while qemu-system and qemu-block-extra:amd64
would be upgraded. This could lead to compute issues.

Change-Id: Ifa474634ebde4cabfded273739eaac5278b63901
Closes-Bug: #1716908
(cherry picked from commit 89b4a78)

vars/ubuntu-16.04.yml

@@ -41,6 +41,8 @@ nova_novnc_distro_packages:
 nova_compute_barbican_distro_packages:
   - cryptsetup
 
+# the qemu-system-.*, qemu-block-extra, qemu-utils, qemu-user packages are explictly listed
+# for consistent upgrades (they will all be to the same version)
 nova_compute_kvm_distro_packages:
   - bridge-utils
   - genisoimage
@@ -57,6 +59,16 @@ nova_compute_kvm_distro_packages:
   - dosfstools
   - dosfstools-dbg
   - multipath-tools
+  - qemu-system
+  - qemu-system-arm
+  - qemu-system-mips
+  - qemu-system-ppc
+  - qemu-system-sparc
+  - qemu-system-x86
+  - qemu-system-misc
+  - qemu-block-extra
+  - qemu-utils
+  - qemu-user
 
 nova_compute_lxd_distro_packages:
   - bridge-utils