qemu: populate <audio> element with default config

Currently the QEMU driver secretly sets the QEMU_AUDIO_DRV env variable

 - VNC - set to "none", unless passthrough of host env variable is set
 - SPICE - always set to "spice"
 - SDL - always passthrough host env
 - No graphics - set to "none", unless passthrough of host env variable is set

The setting of the QEMU_AUDIO_DRV env variable is done in the code which
configures graphics.

If no <audio> element is present, we now auto-populate <audio> elements
to reflect this historical default config. This avoids need to set audio
env when processing graphics.

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

tests/qemustatusxml2xmldata/backup-pull-in.xml

@@ -594,6 +594,7 @@
         <listen type='address' address='127.0.0.1' fromConfig='1' autoGenerated='no'/>
         <image compression='off'/>
       </graphics>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/blockjob-blockdev-in.xml

@@ -694,6 +694,7 @@
         <listen type='address' address='127.0.0.1' fromConfig='1' autoGenerated='no'/>
         <image compression='off'/>
       </graphics>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/blockjob-mirror-in.xml

@@ -103,6 +103,7 @@
       <controller type='pci' index='0' model='pci-root'/>
       <input type='mouse' bus='ps2'/>
       <input type='keyboard' bus='ps2'/>
+      <audio id='1' type='none'/>
       <memballoon model='virtio'>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
       </memballoon>

tests/qemustatusxml2xmldata/migration-in-params-in.xml

@@ -375,6 +375,7 @@
         <listen type='address' address='0.0.0.0' fromConfig='1' autoGenerated='no'/>
         <image compression='off'/>
       </graphics>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/migration-out-nbd-bitmaps-in.xml

@@ -539,6 +539,7 @@
         <alias name='sound0'/>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
       </sound>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/migration-out-nbd-out.xml

@@ -420,6 +420,7 @@
         <alias name='sound0'/>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
       </sound>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/migration-out-nbd-tls-out.xml

@@ -457,6 +457,7 @@
         <alias name='sound0'/>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
       </sound>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/migration-out-params-in.xml

@@ -389,6 +389,7 @@
         <listen type='address' address='0.0.0.0' fromConfig='1' autoGenerated='no'/>
         <image compression='off'/>
       </graphics>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/modern-in.xml

@@ -454,6 +454,7 @@
         <alias name='sound0'/>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
       </sound>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/upgrade-out.xml

@@ -509,6 +509,7 @@
         <alias name='sound0'/>
         <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
       </sound>
+      <audio id='1' type='spice'/>
       <video>
         <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
         <alias name='video0'/>

tests/qemustatusxml2xmldata/vcpus-multi-in.xml

@@ -335,6 +335,7 @@
       </controller>
       <input type='mouse' bus='ps2'/>
       <input type='keyboard' bus='ps2'/>
+      <audio id='1' type='none'/>
       <memballoon model='none'/>
       <iommu model='intel'>
         <driver intremap='on' eim='on'/>