name resolution into IP or IPv6 only, otherwise
we take address family returned by host2sockaddr()
in lsa->sa.sa_family. IOW: "ping ::1" with do IPv6 ping,
"ping 127.0.0.1" will do IPv4 ping.
ping6 is aliased to "ping -6".
Since this is also needed for other applets like telnetd,
introduce generic driver for such things.
It even supports inetd-wait ('linger') mode, when inetd
hands out listen socket to child and waits to it to die,
instead of handing out accepted socket and continuing
listening itself (nowait mode).
Code growth ~200 bytes.
NB: our inetd doesn't support wait mode yet (or mabe it is buggy).
