_pulse_op_cb: fix hang if daemon dies
_pulse_op_cb: fix hang if daemon dies

If PulseAudio daemon died between connect() and a method call that uses
_pulse_op_cb() (e.g. sink_list()), that call would hang indefinitely.

_pulse_state_cb() already detects that the daemon disconnected after the first
pa_mainloop_iterate() and sets _loop_stop. This change makes the _pulse_op_cb
honor _loop_stop and prevents subsequent pa_mainloop_iterate() calls.

mk-fg/python-pulse-control,mk-fg/python-pulse-control