qemu: domain: Add field for storing node name for copy-on-read

The copy-on-read feature is expressed by adding a new node layer in
qemu when using -blockdev. Since we will keep these per-disk (as opposed
to per storage source) we need to store the appropriate node names in
the disk definition.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

tests/qemustatusxml2xmldata/modern-in.xml

@@ -335,6 +335,9 @@
         <address type='pci' domain='0x0000' bus='0x00' slot='0x0b' function='0x0'/>
         <privateData>
           <qom name='virtio-disk1/virtio-backend'/>
+          <nodenames>
+            <nodename type='copyOnRead' name='cor-node'/>
+          </nodenames>
         </privateData>
       </disk>
       <disk type='file' device='cdrom'>