Fix CVE-2019-13224: don't allow different encodings for onig_new_deluxe()
conv_ext0be(const UChar* s, const UChar* end, UChar* conv)
{
  while (s < end) {
    *conv++ = '\0';
    *conv++ = *s++;
  }
}

conv_ext0be(const UChar* s, const UChar* end, UChar* conv)
{
  while (s < end) {
    *conv++ = '\0';
    *conv++ = *s++;
  }
}
