Add more const qualifiers

src/libespeak-ng/compiledict.c

 static void copy_rule_string(char *string, int *state_out)
 {
 	// state 0: conditional, 1=pre, 2=match, 3=post, 4=phonemes
-	static char *const outbuf[5] = { rule_cond, rule_pre, rule_match, rule_post, rule_phonemes };
+	static char * const outbuf[5] = { rule_cond, rule_pre, rule_match, rule_post, rule_phonemes };
 	static const int next_state[5] = { 2, 2, 4, 4, 4 };
 	char *output;
 	char *p;

src/libespeak-ng/dictionary.c

 	char ending[50] = {0};
 
 	// these lists are language specific, but are only relevant if the 'e' suffix flag is used
-	static const char *add_e_exceptions[] = {
+	static const char * const add_e_exceptions[] = {
 		"ion", NULL
 	};
 
-	static const char *add_e_additions[] = {
+	static const char * const add_e_additions[] = {
 		"c", "rs", "ir", "ur", "ath", "ns", "u",
 		"spong", // sponge
 		"rang", // strange

src/libespeak-ng/ssml.c

 		{ NULL,       -1 }
 	};
 
-	static const MNEM_TAB *mnem_tabs[5] = {
+	static const MNEM_TAB * const mnem_tabs[5] = {
 		NULL, mnem_rate, mnem_volume, mnem_pitch, mnem_range
 	};
 
 		{ NULL,      -1 }
 	};
 
-	static const char *prosody_attr[5] = {
+	static const char * const prosody_attr[5] = {
 		NULL, "rate", "volume", "pitch", "range"
 	};
 

src/libespeak-ng/translate.c

 	int n_bytes;
 	int j;
 	int shift;
-	static char unsigned code[4] = { 0, 0xc0, 0xe0, 0xf0 };
+	static const char unsigned code[4] = { 0, 0xc0, 0xe0, 0xf0 };
 
 	if (c < 0x80) {
 		buf[0] = c;