Create an espeak-ng version of espeak_Synchronize.

src/include/espeak-ng/espeak_ng.h

 ESPEAK_NG_API espeak_ng_STATUS
 espeak_ng_Cancel(void);
 
+ESPEAK_NG_API espeak_ng_STATUS
+espeak_ng_Synchronize(void);
+
 ESPEAK_NG_API espeak_ng_STATUS
 espeak_ng_CompileDictionary(const char *dsource,
                             const char *dict_name,

src/libespeak-ng/espeak_api.c

 	return status_to_espeak_error(espeak_ng_Cancel());
 }
 
+ESPEAK_API espeak_ERROR espeak_Synchronize(void)
+{
+	return status_to_espeak_error(espeak_ng_Synchronize());
+}
+
 ESPEAK_API void espeak_CompileDictionary(const char *path, FILE *log, int flags)
 {
 	espeak_ng_CompileDictionary(path, dictionary_name, log, flags);

src/libespeak-ng/speech.c

 static espeak_ng_OUTPUT_MODE my_mode = ENOUTPUT_MODE_SYNCHRONOUS;
 static int out_samplerate = 0;
 static int voice_samplerate = 22050;
-static espeak_ERROR err = EE_OK;
+static espeak_ng_STATUS err = ENS_OK;
 
 t_espeak_callback *synth_callback = NULL;
 int (*uri_callback)(int, const char *, const char *) = NULL;
 				out_samplerate = voice_samplerate;
 				my_audio = wave_open(voice_samplerate, option_device);
 				if (!my_audio) {
-					err = EE_INTERNAL_ERROR;
+					err = ENS_AUDIO_ERROR;
 					return -1;
 				}
 				wave_set_callback_is_output_enabled(fifo_is_command_enabled);
 #endif
 }
 
-ESPEAK_API espeak_ERROR espeak_Synchronize(void)
+ESPEAK_NG_API espeak_ng_STATUS espeak_ng_Synchronize(void)
 {
-	espeak_ERROR berr = err;
+	espeak_ng_STATUS berr = err;
 #ifdef USE_ASYNC
 	while (espeak_IsPlaying())
 		usleep(20000);
 #endif
-	err = EE_OK;
+	err = ENS_OK;
 	return berr;
 }