thing it was still used for was to set the "global default" password
hash.  Since the stock auth.conf contained nothing but comments, the
global default was actually the first algorithm in crypt(3)'s list,
which happens to be DES; I take the fact that nobody noticed as proof
that it was not used outside of crypt(3).

The only other use in our tree was in the Kerberos support code in
in tinyware's passwd(1).  I removed that code in an earlier commit;
it would not have compiled anyway, as it only supported Kerberos IV.

The auth_getval() function is now a stub that always returns NULL,
which has the same effect as a functional auth_getval() with an
empty auth.conf.

MFC after:	3 weeks

o make property_read() take a fd instead to avoid stdio.h mess
o update auth to new interface.

I'll convert sysinstall to use shortly) and a simple call which uses
this mechanism to implement an /etc/auth.conf file.  I'll let Mark Murray
handle the format and checkin of the sample auth.conf file.
Reviewed by:	markm