Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Finally nuke auth.conf, nine years after it was deprecated. The only
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

Tidy up. Sort headers.

Add __FBSDID()s to libutil

Fix a mangled $Id string

o move path in libutil.h to paths.h
o make property_read() take a fd instead to avoid stdio.h mess
o update auth to new interface.

Correct a build error that got past my build test somehow.

Add a simple mechanism for reading property lists from files (which
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