virdbus: Report a debug message that dbus_watch_handle() has failed

Report a debug message if dbus_watch_handle() returns FALSE.
dbus_watch_handle() returns FALSE if there wasn't enough memory for
reading or writing.
Signed-off-by: NMarc Hartmayer <mhartmay@linux.ibm.com>
Reviewed-by: NBjoern Walk <bwalk@linux.ibm.com>
Reviewed-by: NBoris Fiuczynski <fiuczy@linux.ibm.com>
Reviewed-by: NStefan Zimmermann <stzi@linux.ibm.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/util/virdbus.c

@@ -197,7 +197,8 @@ static void virDBusWatchCallback(int fdatch ATTRIBUTE_UNUSED,
     if (events & VIR_EVENT_HANDLE_HANGUP)
         dbus_flags |= DBUS_WATCH_HANGUP;
 
-    (void)dbus_watch_handle(watch, dbus_flags);
+    if (dbus_watch_handle(watch, dbus_flags) == FALSE)
+        VIR_DEBUG("dbus_watch_handle() returned FALSE");
 
     dbus_connection_ref(info->bus);
     while (dbus_connection_dispatch(info->bus) == DBUS_DISPATCH_DATA_REMAINS)