Fix Calibre Companion sync on Linux

- listen(0) doesn't work on Linux, select.select() and socket.accept() return no connection

src/calibre/devices/smart_device_app/driver.py

@@ -1927,7 +1927,7 @@ def _startup_on_demand(self):
                     return message
 
             try:
-                self.listen_socket.listen(0)
+                self.listen_socket.listen(1)
             except:
                 message = 'listen on port %d failed' % port
                 self._debug(message)