viewers: Fix spice audio

Commit 1689ebb25 removed what I thought was an unused audio
handle in the spice viewer code, but apparently it does
something. Strangely some VMs work fine (linux, windows 7),
but my windows 10 VMs need this to actually get audio.
No clue what that's all about

https://bugzilla.redhat.com/show_bug.cgi?id=1881080

Signed-off-by: Cole Robinson <crobinso@redhat.com>

virtManager/details/viewers.py

@@ -476,6 +476,7 @@ class SpiceViewer(Viewer):
         Viewer.__init__(self, *args, **kwargs)
         self._spice_session = None
         self._display = None
+        self._audio = None
         self._main_channel = None
         self._display_channel = None
         self._usbdev_manager = None
@@ -618,6 +619,14 @@ class SpiceViewer(Viewer):
             self._init_widget()
             self.emit("connected")
 
+        elif (type(channel) in [SpiceClientGLib.PlaybackChannel,
+                                SpiceClientGLib.RecordChannel] and
+                                not self._audio):
+            # It's unclear why we need this audio handle, but it
+            # does matter:
+            # https://bugzilla.redhat.com/show_bug.cgi?id=1881080
+            self._audio = SpiceClientGLib.Audio.get(self._spice_session, None)
+
     def _agent_connected_cb(self, src, val):
         self.emit("agent-connected")  # pragma: no cover
 
@@ -631,6 +640,7 @@ class SpiceViewer(Viewer):
             _SIGS.disconnect_obj_signals(self._spice_session)
             self._spice_session.disconnect()
         self._spice_session = None
+        self._audio = None
         if self._display:
             self._display.destroy()
         self._display = None