[iputils][ping] ip address resolution bug

Ping does not ensure it is resolving a hostname to an IPv4 address.
i.e. when setting 'options inet6' in resolv.conf, gethostbyname(3)
returns an IPv6 address, but ping handles it as in IPv4 address.
I attached a simple patch which replaces gethostbyname() with
gethostbyname2(), I'm not sure that is the best way to do it, feel
free to comment.

Quentin Rameau