Changeset b22170c for filter.c

Fix zcrypt when compiling without krb4

OpenSSL's "compatibility" DES API makes des_key_schedule a structure
containing an array, while in krb4 it was an array directly. Thus, we
need to pass a key schedule pointer to owl_zcrypt_string_to_schedule,
instead of passing the key schedule by value. The compatibility macros
defined in OpenSSL's des_old.h allow that function's passing of
*schedule to des_key_sched() to DTRT.

Reviewed-by: Anders Kaseorg <andersk@mit.edu>
Reviewed-by: Nelson Elhage <nelhage@mit.edu>