remove unused int option_tone2

It is set in voices.c but never used. docs/voices.md indicates that the keyword intonation only takes one parameter, confirming that option_tone2 is unused.

src/libespeak-ng/translate.c

 static char translator2_language[20] = { 0 };
 
 FILE *f_trans = NULL; // phoneme output text
-int option_tone2 = 0;
 int option_tone_flags = 0; // bit 8=emphasize allcaps, bit 9=emphasize penultimate stress
 int option_phonemes = 0;
 int option_phoneme_events = 0;

src/libespeak-ng/translate.h

 	int clause_terminator;
 } Translator;
 
-extern int option_tone2;
 #define OPTION_EMPHASIZE_ALLCAPS  0x100
 #define OPTION_EMPHASIZE_PENULTIMATE 0x200
 extern int option_tone_flags;

src/libespeak-ng/voices.c

 			stress_add_set = Read8Numbers(p, stress_add);
 			break;
 		case V_INTONATION: // intonation
-			sscanf(p, "%d %d", &option_tone_flags, &option_tone2);
+			sscanf(p, "%d", &option_tone_flags);
 			if ((option_tone_flags & 0xff) != 0) {
 				if (langopts)
 					langopts->intonation_group = option_tone_flags & 0xff;