The idea is to prevent needing to patch source files for packages that
use OpenSSL for DES support by ensuring that including <openssl/des.h>
will always present the old DES API.
(1) If des_old.h exists, then we're using OpenSSL>=0.9.7, and
<openssl/des.h> already does the right thing.
(2) If des_old.h doesn't exist, then one of two things is happening:
(a) If <openssl/des.h> is old and (only) supports the old DES API,
then <openssl/des.h> does the right thing.
(b) If it's NetBSD's Special(TM) one that stripped out the old DES
support into a separate library and header (-ldes, <des.h>),
then we create a new header <openssl/des.h> that includes the
system one and <des.h>.
Also modify existing packages that set USE_OLD_DES_API to simply include
<openssl/des.h> instead of either <des.h> or <openssl/des_old.h> (This
step is mostly just removing unnecessary patches).
This should fix building packages that use OpenSSL's old DES API support
on non-NetBSD systems where the built-in OpenSSL is at least 0.9.7.
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