Massive change to add foundational support for IPv6.

	Massive change to add foundational support for IPv6.

	Most of the code is still hard-coded to use IPv6, and there are
	assertions sprinkled throughout which will cause the server to
	die if IPv6 is used.  However, the data structures are there,
	and most of the support functions.  The next step is updating
	the client code to look for IPv6 clients, and to listen on IPv6
	sockets.

	radiusd & radclient work.  radrelay & radsqlrelay build.

	Most of the modules work.  rlm_sql doesn't (as yet).