rem: make_printable_char (unsigned int c)
add: make_printable_char (unsigned char c)
context: make_printable_char (unsigned int c){  char *buf = xmalloc (5);  assert (c < N_CHARS);  if (ISPRINT (c))    {      buf[0] = c;      buf[1] = '\0';    }  else    {      sprintf (buf, "\\%03o", c);    }  return buf;}