inet_pton() included in src/lib/libc/net is not spec conformant.

	inet_pton() must not allow shortened IPv4 addresses, like:
		10		for 10.0.0.0
		10.1		for 10.0.0.1
		10.0.1		for 10.0.0.1
	(see RFC2553 6.6) but the current code allows it.

	What is the right thing to happen?
	- fix it, some may react that "ftp 10.1" does not work
	- leave it

	Note that getaddrinfo() currently calls inet_pton() internally,
	and changing behavior of inet_pton() will affect behavior of
	telnet, ftp or whatever else.  actually RFC2553 is silent about
	getaddrinfo() behavior in this case (should/should not accept
	shortened form).

itojun