Revert "code cleanup: change global int current_phoneme table to static"

This works around issue 915

src/libespeak-ng/phoneme.h

 // Several phoneme tables may be loaded into memory. phoneme_tab points to
 // one for the current voice
 extern int n_phoneme_tab;
+extern int current_phoneme_table;
 extern PHONEME_TAB *phoneme_tab[N_PHONEME_TAB];
 
 typedef struct {

src/libespeak-ng/synthdata.c

 
 // copy the current phoneme table into here
 int n_phoneme_tab;
+int current_phoneme_table;
 PHONEME_TAB *phoneme_tab[N_PHONEME_TAB];
 
 unsigned short *phoneme_index = NULL;
 	}
 }
 
-int SelectPhonemeTable(int number)
+void SelectPhonemeTable(int number)
 {
 	n_phoneme_tab = 0;
 	SetUpPhonemeTable(number); // recursively for included phoneme tables
 	n_phoneme_tab++;
-	return number;
+	current_phoneme_table = number;
 }
 
 int LookupPhonemeTable(const char *name)

src/libespeak-ng/synthdata.h

 		PHONEME_LIST *plist);
 
 int PhonemeCode(unsigned int mnem);
-int SelectPhonemeTable(int number);
+void SelectPhonemeTable(int number);
 int  SelectPhonemeTableName(const char *name);
 
 #ifdef __cplusplus

src/libespeak-ng/synthesize.c

 		return 0;
 	}
 
+	if (current_phoneme_table != voice->phoneme_tab_ix)
+		SelectPhonemeTable(voice->phoneme_tab_ix);
+
 	// read the next clause from the input text file, translate it, and generate
 	// entries in the wavegen command queue
 	TranslateClause(translator, &clause_tone, &voice_change);