Remove calls to wave_is_busy.

Removing these calls do not impact on the behaviour of the program
and simplify the wave.h API.

src/libespeak-ng/fifo.c

 	//
 	int i = 0;
 	while ((i <= MAX_INACTIVITY_CHECK) && !a_start_is_required) {
-		if (wave_is_busy(NULL))
-			i = 0;
-		else
-			i++;
+		i++;
 
 		int err = 0;
 		struct timespec ts;

src/libespeak-ng/speech.c

 
 ESPEAK_API int espeak_IsPlaying(void)
 {
-	if (((my_mode & ENOUTPUT_MODE_SPEAK_AUDIO) == ENOUTPUT_MODE_SPEAK_AUDIO) && wave_is_busy(my_audio))
-		return 1;
-
 #ifdef USE_ASYNC
 	return fifo_is_busy();
 #else

src/libespeak-ng/wave.c

 void *wave_port_open(int, const char *);
 size_t wave_port_write(void *theHandler, char *theMono16BitsWaveBuffer, size_t theSize);
 int wave_port_close(void *theHandler);
-int wave_port_is_busy(void *theHandler);
 void wave_port_terminate();
 void wave_port_flush(void *theHandler);
 void *wave_port_test_get_write_buffer();
 void *wave_pulse_open(int, const char *);
 size_t wave_pulse_write(void *theHandler, char *theMono16BitsWaveBuffer, size_t theSize);
 int wave_pulse_close(void *theHandler);
-int wave_pulse_is_busy(void *theHandler);
 void wave_pulse_terminate();
 void wave_pulse_flush(void *theHandler);
 void *wave_pulse_test_get_write_buffer();
 		return wave_port_close(theHandler);
 }
 
-int wave_is_busy(void *theHandler)
-{
-	if (pulse_running)
-		return wave_pulse_is_busy(theHandler);
-	else
-		return wave_port_is_busy(theHandler);
-}
-
 void wave_terminate()
 {
 	if (pulse_running)
 #define wave_open wave_port_open
 #define wave_write wave_port_write
 #define wave_close wave_port_close
-#define wave_is_busy wave_port_is_busy
 #define wave_terminate wave_port_terminate
 #define wave_flush wave_port_flush
 
 		if (0 != wave_open_sound())
 			return 0;
 		my_stream_could_start = 1;
-	} else if (!wave_is_busy(NULL))
-		my_stream_could_start = 1;
+	}
 	assert(BUFFER_LENGTH >= bytes_to_write);
 
 	if (myWrite >= myBuffer + BUFFER_LENGTH)
 	return 0;
 }
 
-int wave_is_busy(void *theHandler)
-{
-	(void)theHandler; // unused
-
-	PaError active = 0;
-
-	if (pa_stream) {
-#if USE_PORTAUDIO == 18
-		active = Pa_StreamActive(pa_stream)
-		         && (mInCallbackFinishedState == false);
-#else
-		active = Pa_IsStreamActive(pa_stream)
-		         && (mInCallbackFinishedState == false);
-#endif
-	}
-
-	return active == 1;
-}
-
 void wave_terminate()
 {
 	Pa_Terminate();
 	return 0;
 }
 
-int wave_is_busy(void *theHandler)
-{
-	(void)theHandler; // unused
-
-	return 0;
-}
-
 void wave_terminate()
 {
 }

src/libespeak-ng/wave.h

 extern size_t wave_write(void *theHandler, char *theMono16BitsWaveBuffer, size_t theSize);
 extern int wave_close(void *theHandler);
 extern void wave_flush(void *theHandler);
-extern int wave_is_busy(void *theHandler);
 extern void wave_terminate();
 
 // general functions

src/libespeak-ng/wave_pulse.c

 #define wave_open wave_pulse_open
 #define wave_write wave_pulse_write
 #define wave_close wave_pulse_close
-#define wave_is_busy wave_pulse_is_busy
 #define wave_terminate wave_pulse_terminate
 #define wave_flush wave_pulse_flush
 
 	return PULSE_OK;
 }
 
-int wave_is_busy(void *theHandler)
-{
-	(void)theHandler; // unused
-
-	pa_timing_info a_timing_info = {0};
-	int active = pulse_playing(&a_timing_info);
-	return active;
-}
-
 void wave_terminate()
 {
 	pthread_mutex_t *a_mutex = NULL;