pulse backend: correct declaration of function with no parameters

We have to use void in a function declaration if we want no function
parameters. Using just empty parenthesis means the function takes an
unspecified number of parameters.

We had it correct for most declarations and this series fixes it for
the rest.

Thanks for the sparse semantic parser for pointing this out.

src/modules/mixer/lib/backends/pulseaudio/pulse.c

@@ -672,7 +672,7 @@ _subscribe_cb(pa_context *c, pa_subscription_event_type_t t,
 }
 
 static Eina_Bool _pulse_connect(void *data);
-static void _disconnect_cb();
+static void _disconnect_cb(void);
 
 static void
 _pulse_pa_state_cb(pa_context *context, void *data)