* tools/pkcs1-conv.c: Updated for dsa/der interface change.

* der2dsa.c (dsa_public_key_from_der_iterators): Split into two
new functions...
(dsa_params_from_der_iterator): New function.
(dsa_public_key_from_der_iterator): New function.
(dsa_openssl_private_key_from_der_iterator): Renamed, was
dsa_private_key_from_der_iterator.
(dsa_openssl_private_key_from_der): Likewise.
* dsa.h: Corresponding changees to prototypes and #defines.

Rev: nettle/ChangeLog:1.45
Rev: nettle/der2dsa.c:1.3
Rev: nettle/dsa.h:1.3
Rev: nettle/tools/pkcs1-conv.c:1.3