`IPAddr.ntop` takes the binary representation of an IP address, whose
length should be 4 or 16 *bytes* (not characters/codepoints).
The current implementation accepts strings in any encoding, but for
some values in non-BINARY encoding, it fails proper length check and
raises an `AddressFamilyError`. Since passing strings in a multibyte
encoding has never worked correctly for years, this patch makes it an
explicit error with an `InvalidAddressError`.
Fixes: https://github.com/ruby/ipaddr/issues/56https://github.com/ruby/ipaddr/commit/a33fd14d4a
eb53131367