struct ifreq (used by SIOCGIFCONF, in sys/net/if.h) is used as
	packed struct.  Do anyone object to put __attribute__ ((__packed__))
	to the structure?  Since it does not come with the attribute
	there has been many SEGV on alignment-picky architecutres.

	this is one of the motivation for migrating to getifaddrs(3), however,
	SIOCGIFCONF is widely used (and it is VERY hard to use SIOCGIFCONF
	100% correctly) so I think putting the attribute is more safe.

itojun