code cleanup: remove static from WordToString

src/libespeak-ng/compiledata.c

 static void EndPhonemeTable(CompileContext *ctx)
 {
 	int ix;
+	char buf[5];
 
 	if (ctx->n_phoneme_tabs == 0)
 		return;
 	for (ix = 0; ix < ctx->n_phcodes; ix++) {
 		if (ctx->phoneme_tab2[ix].type == phINVALID) {
 			error(ctx, "Phoneme [%s] not declared, referenced at line %d",
-			      WordToString(ctx->phoneme_tab2[ix].mnemonic), (int)(ctx->phoneme_tab2[ix].program));
+			      WordToString(buf, ctx->phoneme_tab2[ix].mnemonic), (int)(ctx->phoneme_tab2[ix].program));
 			ctx->error_count++;
 			ctx->phoneme_tab2[ix].type = 0; // prevent the error message repeating
 		}

src/libespeak-ng/synth_mbrola.c

 	const char *final_pitch;
 	char *ptr;
 	char mbr_buf[120];
+	char phbuf[5];
 
 	static int phix;
 	static int embedded_ix;
 			DoPhonemeMarker(espeakEVENT_PHONEME, (p->sourceix & 0x7ff) + clause_start_char, 0, phoneme_name);
 		}
 
-		ptr += sprintf(ptr, "%s\t", WordToString(name));
+		ptr += sprintf(ptr, "%s\t", WordToString(phbuf, name));
 
 		if (name2 == '_') {
 			// add a pause after this phoneme
 				ptr += sprintf(ptr, "%d\t%s", len1, pitch);
 
 				pitch = WritePitch(p->env, p->pitch1, p->pitch2, -len_percent, 0);
-				ptr += sprintf(ptr, "%s\t%d\t%s", WordToString(name2), len-len1, pitch);
+				ptr += sprintf(ptr, "%s\t%d\t%s", WordToString(phbuf, name2), len-len1, pitch);
 			}
 			done = true;
 			break;
 		if (!done) {
 			if (name2 != 0) {
 				len1 = (len * len_percent)/100;
-				ptr += sprintf(ptr, "%d\n%s\t", len1, WordToString(name2));
+				ptr += sprintf(ptr, "%d\n%s\t", len1, WordToString(phbuf, name2));
 				len -= len1;
 			}
 			ptr += sprintf(ptr, "%d%s\n", len, final_pitch);

src/libespeak-ng/synthdata.c

 
 static void InvalidInstn(PHONEME_TAB *ph, int instn)
 {
-	fprintf(stderr, "Invalid instruction %.4x for phoneme '%s'\n", instn, WordToString(ph->mnemonic));
+	char buf[5];
+	fprintf(stderr, "Invalid instruction %.4x for phoneme '%s'\n", instn, WordToString(buf, ph->mnemonic));
 }
 
 static bool StressCondition(Translator *tr, PHONEME_LIST *plist, int condition, int control)

src/libespeak-ng/synthesize.c

 #define RMS_START 28  // 28
 #define VOWEL_FRONT_LENGTH  50
 
-const char *WordToString(unsigned int word)
+const char *WordToString(char buf[5], unsigned int word)
 {
 	// Convert a phoneme mnemonic word into a string
 	int ix;
-	static char buf[5];
-
-	MAKE_MEM_UNDEFINED(&buf, sizeof(buf));
 
 	for (ix = 0; ix < 4; ix++)
 		buf[ix] = word >> (ix*8);

src/libespeak-ng/synthesize.h

 int DoSample3(PHONEME_DATA *phdata, int length_mod, int amp);
 int DoSpect2(PHONEME_TAB *this_ph, int which, FMT_PARAMS *fmt_params,  PHONEME_LIST *plist, int modulation);
 int PauseLength(int pause, int control);
-const char *WordToString(unsigned int word);
+const char *WordToString(char buf[5], unsigned int word);
 
 #ifdef __cplusplus
 }