code cleanup: remove wavefile_ix, move wavefile_amp

wavefile_ix is always equal to fmt_params->wav_addr.

wavefile_amp is only used once  so it can be set right
before calling DoSample2().

src/libespeak-ng/synthdata.c

 PHONEME_TAB_LIST phoneme_tab_list[N_PHONEME_TABS];
 int phoneme_tab_number = 0;
 
-int wavefile_ix; // a wavefile to play along with the synthesis
-int wavefile_amp;
-
 int seq_len_adjust;
 
 static espeak_ng_STATUS ReadPhFile(void **ptr, const char *fname, int *size, espeak_ng_ERROR_CONTEXT *context)
 			}
 			nf++;
 		}
-		wavefile_ix = 0;
 	}
 
 	if (length1 > 0) {

src/libespeak-ng/synthesize.c

 	if (voice->klattv[0])
 		wcmd_spect = WCMD_KLATT;
 
-	wavefile_ix = fmt_params->wav_addr;
-
-	if (fmt_params->wav_amp == 0)
-		wavefile_amp = 32;
-	else
-		wavefile_amp = (fmt_params->wav_amp * 32)/100;
-
-	if (wavefile_ix == 0) {
+	if (fmt_params->wav_addr == 0) {
 		if (wave_flag) {
 			// cancel any wavefile that was playing previously
 			wcmd_spect = WCMD_SPECT2;
 		if ((fmt_params->wav_addr != 0) && ((frame1->frflags & FRFLAG_DEFER_WAV) == 0)) {
 			// there is a wave file to play along with this synthesis
 			seq_len_adjust = 0;
+	
+			int wavefile_amp;
+			if (fmt_params->wav_amp == 0)
+				wavefile_amp = 32;
+			else
+				wavefile_amp = (fmt_params->wav_amp * 32)/100;
+
 			DoSample2(fmt_params->wav_addr, which+0x100, 0, fmt_params->fmt_control, 0, wavefile_amp);
 			wave_flag = 1;
-			wavefile_ix = 0;
 			fmt_params->wav_addr = 0;
 		}
 

src/libespeak-ng/synthesize.h

 extern int samplerate;
 extern int samplerate_native;
 
-extern int wavefile_ix;
-extern int wavefile_amp;
-
 #define N_ECHO_BUF 5500   // max of 250mS at 22050 Hz
 extern int echo_head;
 extern int echo_tail;