ifconfig accepting hostname as ipv4 address

[Wojciech Puchar]

> input.
> Moreover, ifconfig em0 some_valid_fqdn/MASK silently ignores it, so you can't 
> set valid CIDR address using this notation.
>
> Classful era has ended more than 10 years ago, do we still want to keep this 
> behavior?
>
were not aware of that option, and it is rather stupid option - you should
work on addresses not names when configuring network