Remove unused variables.

src/libespeak-ng/mbrowrap.c

 
 char *lastErrorStr_mbrola(char *buffer, int bufsize)
 {
-	int result;
 	if (mbr_pid)
 		mbrola_has_errors();
-	result = snprintf(buffer, bufsize, "%s", mbr_errorbuf);
+	snprintf(buffer, bufsize, "%s", mbr_errorbuf);
 	return buffer;
 }
 

src/libespeak-ng/voices.c

 	char names[8][40];
 	char name1[40];
 	char name2[80];
-	const char *voice_dir;
 
 	int pitch1;
 	int pitch2;