dirmngr: Support ECDSA for OCSP.
* dirmngr/validate.c (pk_algo_from_sexp): Make public. Support ECC. * dirmngr/ocsp.c (check_signature): Remove hash preparation out to ... (check_signature_core): here. This changes the arg s_hash to md. Support ECDSA.
The test was done with my qualified signature certificate from the
Telesec and their responder http://tqrca1.ocsp.telesec.de/ocspr .
See also libksba commit rK24992a4a7a61d93759e1dbd104b845903d4589bf
(cherry picked from commit 890e9849b58e91fb7e0ad8d3b11d19363fca2d8a)