Remove the now unused option_multibyte variable.

src/libespeak-ng/speech.c

 	if ((outbuf == NULL) || (event_list == NULL))
 		return ENS_NOT_INITIALIZED;
 
-	option_multibyte = flags & 7;
 	option_ssml = flags & espeakSSML;
 	option_phoneme_input = flags & espeakPHONEMES;
 	option_endpause = flags & espeakENDPAUSE;

src/libespeak-ng/translate.c

 
 wchar_t option_punctlist[N_PUNCTLIST] = { 0 };
 char ctrl_embedded = '\001'; // to allow an alternative CTRL for embedded commands
-int option_multibyte = espeakCHARS_AUTO; // 0=auto, 1=utf8, 2=8bit, 3=wchar, 4=16bit
 
 // these are overridden by defaults set in the "speak" file
 int option_linelength = 0;

src/libespeak-ng/translate.h

 extern int option_phonemes;
 extern int option_phoneme_events;
 extern int option_linelength;     // treat lines shorter than this as end-of-clause
-extern int option_multibyte;
 extern int option_capitals;
 extern int option_punctuation;
 extern int option_endpause;