i2d_PrivateKey_bio
i = i2d_PrivateKey_bio(out, pkey);
rv = i2d_PrivateKey_bio(mem_out, pkey);
i2d_PrivateKey_bio(out, pkey);
if (!i2d_PrivateKey_bio(out, pkey))
if (privbio == NULL || i2d_PrivateKey_bio(privbio, pkey) <= 0)
int i2d_PrivateKey_bio(BIO *bp, const EVP_PKEY *pkey);