boost::asio::ip::network_v6::hosts has a BUG to represent address_v6_range of "::/0"

code position: https://github.com/boostorg/asio/blob/e65367991cb5fbdb8a7cf218ae38f69ca9a0a9f5/include/boost/asio/ip/impl/network_v6.ipp#L78

```cpp
address_v6_range network_v6::hosts() const noexcept
{
address_v6::bytes_type begin_bytes(address_.to_bytes());
address_v6::bytes_type end_bytes(address_.to_bytes());
for (std::size_t i = 0; i < 16; ++i)
{
if (prefix_length_ <= i * 8)
{
begin_bytes[i] = 0;
end_bytes[i] = 0xFF;
}
else if (prefix_length_ < (i + 1) * 8)
{
begin_bytes[i] &= 0xFF00 >> (prefix_length_ % 8);
end_bytes[i] |= 0xFF >> (prefix_length_ % 8);
}
}
return address_v6_range(
address_v6_iterator(address_v6(begin_bytes, address_.scope_id())),
++address_v6_iterator(address_v6(end_bytes, address_.scope_id())));
}
```

The above code returns an address_v6_range with the end being `++address_v6_iterator(address_v6(end_bytes, address_.scope_id())));`.
If the network CIDR is `::/0`, which should contains all valid ipv6 addresses, the `end_bytes` will be `0xFFF...FFF`.
And the `++` operator will make the address_v6_range [0x00..00, ***\+\+ 0xFF...FF***) overflow to [0x00..00, 0x00..00). This network range contains no ipv6 addresses.