code cleanup: remove phoneme_tab_flags

It is memset and set once, but never checked or used for anything.

src/libespeak-ng/phoneme.h

 // one for the current voice
 extern int n_phoneme_tab;
 extern PHONEME_TAB *phoneme_tab[N_PHONEME_TAB];
-extern unsigned char phoneme_tab_flags[N_PHONEME_TAB];  // bit 0: not inherited
 
 typedef struct {
 	char name[N_PHONEME_TAB_NAME];

src/libespeak-ng/synthdata.c

 // copy the current phoneme table into here
 int n_phoneme_tab;
 PHONEME_TAB *phoneme_tab[N_PHONEME_TAB];
-unsigned char phoneme_tab_flags[N_PHONEME_TAB];   // bit 0: not inherited
 
 unsigned short *phoneme_index = NULL;
 char *phondata_ptr = NULL;
 	int ph_code;
 	PHONEME_TAB *phtab;
 
-	if (recursing == false)
-		memset(phoneme_tab_flags, 0, sizeof(phoneme_tab_flags));
-
 	if ((includes = phoneme_tab_list[number].includes) > 0) {
 		// recursively include base phoneme tables
 		SetUpPhonemeTable(includes-1, true);
 		phoneme_tab[ph_code] = &phtab[ix];
 		if (ph_code > n_phoneme_tab)
 			n_phoneme_tab = ph_code;
-
-		if (recursing == 0)
-			phoneme_tab_flags[ph_code] |= 1; // not inherited
 	}
 }