ECC: use OID encoding if possible
ECC: use OID encoding if possible

Instead of explicitly encoding the domain, encode them with the
OID if the OID is available.  This makes the ecdsa_sign test
run with OpenSSL, since OpenSSL needs the OID explicitly set.

Rohde-Schwarz-Cybersecurity/botan,randombit/botan,randombit/botan,randombit/botan,webmaster128/botan,Rohde-Schwarz-Cybersecurity/botan,webmaster128/botan,randombit/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,Rohde-Schwarz-Cybersecurity/botan,randombit/botan,webmaster128/botan,webmaster128/botan,webmaster128/botan