definition of "AF_INET6". Declare those functions and, if it's not
defined, define "AF_INET6" in "inet_v6defs.h", and arrange to include
it if "inet_ntop()" is missing. (Systems will probably have both of
them or lack both of them, and we may choose not to use the system's
"inet_pton()" because it's buggy, so base the decision on whether to
include "inet_v6defs.h" on whether we're using the system's
"inet_ntop()" or not.) Fix some macro references in "Makefile.am" and
"configure.in".
svn path=/trunk/; revision=830
Guy Harris