SSL_get_shared_sigalgs
nsig = SSL_get_shared_sigalgs(s, 0, NULL, NULL, NULL, NULL, NULL);
SSL_get_shared_sigalgs(s, i, &sign_nid, &hash_nid, NULL,
int SSL_get_shared_sigalgs(SSL *s, int idx,
numshared = SSL_get_shared_sigalgs(serverssl, 0, &sig, &hash,