cleanup: refactor and remove duplication from SetSpeed() implementations.

There are two SetSpeed(), one for Sonic and one without. The differences
are very small.

In SetSpeedMods(), sample rate is adjusted for Sonic only:
 speed.min_sample_len = (speed.min_sample_len * samplerate_native) / 22050;

Since samplerate_native is 22050 at the moment this line has no effect.

src/libespeak-ng/setlengths.c

 #include "synthesize.h"
 #include "translate.h"
 
+static void SetSpeedMods(int wpm, int x);
+
 extern int saved_parameters[];
 
 // convert from words-per-minute to internal speed factor
 void SetSpeed(int control)
 {
 	int x;
-	int s1;
 	int wpm;
 	int wpm2;
 	int wpm_value;
 	}
 
 	if (control & 2) {
-		// these are used in synthesis file
-
-		if (wpm > 350) {
-			speed.lenmod_factor = 85 - (wpm - 350) / 3;
-			speed.lenmod2_factor = 60 - (wpm - 350) / 8;
-		} else if (wpm > 250) {
-			speed.lenmod_factor = 110 - (wpm - 250)/4;
-			speed.lenmod2_factor = 110 - (wpm - 250)/2;
-		}
-
-		s1 = (x * voice->speedf1)/256;
-
-		if (wpm >= 170)
-			speed.wav_factor = 110 + (150*s1)/128; // reduced speed adjustment, used for playing recorded sounds
-		else
-			speed.wav_factor = 128 + (128*s1)/130; // = 215 at 170 wpm
-
-		if (wpm >= 350)
-			speed.wav_factor = wav_factor_350[wpm-350];
-
-		if (wpm >= 390) {
-			speed.min_sample_len = espeakRATE_MAXIMUM - (wpm - 400)/2;
-			if (wpm > 440)
-				speed.min_sample_len = 420 - (wpm - 440);
-		}
-
-		// adjust for different sample rates
-		speed.min_sample_len = (speed.min_sample_len * samplerate_native) / 22050;
-
-		speed.pause_factor = (256 * s1)/115; // full speed adjustment, used for pause length
-		speed.clause_pause_factor = 0;
-
-		if (wpm > 430)
-			speed.pause_factor = 12;
-		else if (wpm > 400)
-			speed.pause_factor = 13;
-		else if (wpm > 374)
-			speed.pause_factor = 14;
-		else if (wpm > 350)
-			speed.pause_factor = pause_factor_350[wpm - 350];
-
-		if (speed.clause_pause_factor == 0) {
-			// restrict the reduction of pauses between clauses
-			if ((speed.clause_pause_factor = speed.pause_factor) < 16)
-				speed.clause_pause_factor = 16;
-		}
-	}
+    		SetSpeedMods(wpm, x);
+    	}
 }
 
 #else
 {
 	// This is the earlier version of SetSpeed() before sonic speed-up was added
 	int x;
-	int s1;
 	int wpm;
 	int wpm2;
 
 	}
 
 	if (control & 2) {
-		// these are used in synthesis file
-
-		if (wpm > 350) {
-			speed.lenmod_factor = 85 - (wpm - 350) / 3;
-			speed.lenmod2_factor = 60 - (wpm - 350) / 8;
-		} else if (wpm > 250) {
-			speed.lenmod_factor = 110 - (wpm - 250)/4;
-			speed.lenmod2_factor = 110 - (wpm - 250)/2;
-		}
+		SetSpeedMods(wpm, x);
+	}
+}
 
-		s1 = (x * voice->speedf1)/256;
+#endif
 
-		if (wpm >= 170)
-			speed.wav_factor = 110 + (150*s1)/128; // reduced speed adjustment, used for playing recorded sounds
-		else
-			speed.wav_factor = 128 + (128*s1)/130; // = 215 at 170 wpm
+static void SetSpeedMods(int wpm, int x) {
+	// these are used in synthesis file
 
-		if (wpm >= 350)
-			speed.wav_factor = wav_factor_350[wpm-350];
+	if (wpm > 350) {
+		speed.lenmod_factor = 85 - (wpm - 350) / 3;
+		speed.lenmod2_factor = 60 - (wpm - 350) / 8;
+	} else if (wpm > 250) {
+		speed.lenmod_factor = 110 - (wpm - 250)/4;
+		speed.lenmod2_factor = 110 - (wpm - 250)/2;
+	}
 
-		if (wpm >= 390) {
-			speed.min_sample_len = espeakRATE_MAXIMUM - (wpm - 400)/2;
-			if (wpm > 440)
-				speed.min_sample_len = 420 - (wpm - 440);
-		}
 
-		speed.pause_factor = (256 * s1)/115; // full speed adjustment, used for pause length
-		speed.clause_pause_factor = 0;
-
-		if (wpm > 430)
-			speed.pause_factor = 12;
-		else if (wpm > 400)
-			speed.pause_factor = 13;
-		else if (wpm > 374)
-			speed.pause_factor = 14;
-		else if (wpm > 350)
-			speed.pause_factor = pause_factor_350[wpm - 350];
-
-		if (speed.clause_pause_factor == 0) {
-			// restrict the reduction of pauses between clauses
-			if ((speed.clause_pause_factor = speed.pause_factor) < 16)
-				speed.clause_pause_factor = 16;
-		}
+	int s1 = (x * voice->speedf1)/256;
+
+	if (wpm >= 170)
+		speed.wav_factor = 110 + (150*s1)/128; // reduced speed adjustment, used for playing recorded sounds
+	else
+		speed.wav_factor = 128 + (128*s1)/130; // = 215 at 170 wpm
+
+	if (wpm >= 350)
+		speed.wav_factor = wav_factor_350[wpm-350];
+
+	if (wpm >= 390) {
+		speed.min_sample_len = espeakRATE_MAXIMUM - (wpm - 400)/2;
+		if (wpm > 440)
+			speed.min_sample_len = 420 - (wpm - 440);
 	}
-}
 
+#if HAVE_SONIC_H
+	// adjust for different sample rates
+	speed.min_sample_len = (speed.min_sample_len * samplerate_native) / 22050;
 #endif
 
+	speed.pause_factor = (256 * s1)/115; // full speed adjustment, used for pause length
+	speed.clause_pause_factor = 0;
+
+	if (wpm > 430)
+		speed.pause_factor = 12;
+	else if (wpm > 400)
+		speed.pause_factor = 13;
+	else if (wpm > 374)
+		speed.pause_factor = 14;
+	else if (wpm > 350)
+		speed.pause_factor = pause_factor_350[wpm - 350];
+
+	if (speed.clause_pause_factor == 0) {
+		// restrict the reduction of pauses between clauses
+		if ((speed.clause_pause_factor = speed.pause_factor) < 16)
+			speed.clause_pause_factor = 16;
+	}
+}
+
 espeak_ng_STATUS SetParameter(int parameter, int value, int relative)
 {
 	// parameter: reset-all, amp, pitch, speed, linelength, expression, capitals, number grouping