[most importantly] put back dependencies accidentaly eliminated in
check-in #13342.

if $(EXHEADER) is empty.

Notified by many, solution suggested by Carson Gaspar <carson@taltos.org>

the Makefiles. NB: this commit is probably going to generate a huge posting
and it is highly uninteresting to read.

This is part of a large change submitted by Markus Friedl <markus@openbsd.org>

Submitted by: Thierry Lelegard <thierry.lelegard@canal-plus.fr>

PR: 461

give it.
For 0.9.7 and up, that means util/domd needs to remove those double
dashes from the argument list when gcc is used to find the
dependencies.

handled properly.
Part of PR 75

functions in ui_compat.  This gave reason to rework that part more
thoroughly, so here are the changes made:

1. Add DES_read_password() and DES_read_2passwords() with the same
   functionality as the corresponding old des_ functions, as a
   convenience to the users.
2. Add UI_UTIL_read_pw_string() and UI_UTIL_read_pw() with the
   functionality from des_read_pw_string() and des_read_pw(), again as
   a concenience to the users.
3. Rename des_read_password(), des_read_2passwords(),
   des_read_pw_string() and des_read_pw() by changing des_ to
   _ossl_old_des_, and add the usual mapping macros.
4. Move the implementation of des_read_password() and
   des_read_2passwords() to the des directory, since they are tightly
   tied to DES anyway.

This change was inspired by a patch from Assar Westerlund <assar@sics.se>:

There are some functions that didn't get the kick-away-old-des-and-
replace-des-with-DES action.  Here's a patch that adds DES_ and des_
(in des_old.h) versions of des_read_pw_string et al.  This patch
includes some of the first des_old.h semi-colon macro fixes that I've
already sent.

libeay.num got tweaked so the old des symbols would retain their
positions.

section.

Add ui_compat.h for inclusion by those who want the old functions and
provide all of them, not just the higher-level ones, in ui_compat.c.

like des_read_password and friends (backward compatibility functions
using this new API are provided).  The purpose is to remove prompting
functions from the DES code section as well as provide for prompting
through dialog boxes in a window system and the like.