add notice about SIOCGIFCONF case (not LP64 friendly, does not try-and-error for memory region size)
add notice about SIOCGIFCONF case (not LP64 friendly, does not try-and-error
for memory region size)

MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame,MarginC/kame