csr verification with openssl gives error for ed25519 certificates

In tests/openssl.rs, invocation of the verify_csr(&cert); function is commented out for ed25519 certificates because it fails. I'm not sure what the problem is.

This is the output if you remove the //:

---- test_openssl_25519_given stdout ----
-----BEGIN CERTIFICATE-----
MIIBLzCB4qADAgECAgEqMAUGAytlcDAsMSowFgYDVQQKDA9DcmFiIHdpZGdpdHMg
U0UwEAYDVQQDDAlNYXN0ZXIgQ0EwIhgPMTk3NTAxMDEwMDAwMDBaGA80MDk2MDEw
MTAwMDAwMFowLDEqMBYGA1UECgwPQ3JhYiB3aWRnaXRzIFNFMBAGA1UEAwwJTWFz
dGVyIENBMCowBQYDK2VwAyEA67x/8fDcfbp7bLnOhE/nHt8Oz0ri2PAS1nB3Vwxr
5ECjJTAjMCEGA1UdEQQaMBiCC2NyYWJzLmNyYWJzgglsb2NhbGhvc3QwBQYDK2Vw
A0EANUf5PpvKy0FIAHybycyZZViPYXndWjFMPSLMH9qNmKo3VnsCwjWlboetGT6i
j3popEMaJ8nhDP4AAqo+/c/vDA==
-----END CERTIFICATE-----

-----BEGIN CERTIFICATE REQUEST-----
MIHiMIGVAgEAMC4xGDAWBgNVBAoMD0NyYWIgd2lkZ2l0cyBTRTESMBAGA1UEAwwJ
TWFzdGVyIENBMCowBQYDK2VwAyEA67x/8fDcfbp7bLnOhE/nHt8Oz0ri2PAS1nB3
Vwxr5ECgNDAyBgkqhkiG9w0BCQ4xJTAjMCEGA1UdEQQaMBiCC2NyYWJzLmNyYWJz
gglsb2NhbGhvc3QwBQYDK2VwA0EAbXjjM1CwFLPPCMRDNtt0SnVLvD7gv70Hj9TA
UWb1oFnKmIu9qQOXOW7xb5YHGcwPyo0zTpBU5vukDFkraojhDg==
-----END CERTIFICATE REQUEST-----

thread 'test_openssl_25519_given' panicked at 'called `Result::unwrap()` on an `Err` value: ErrorStack([Error { code: 218529960, library: "asn1 encoding routines", function: "asn1_check_tlen", reason: "wrong tag", file: "../crypto/asn1/tasn_dec.c", line: 1130 }, Error { code: 218546234, library: "asn1 encoding routines", function: "asn1_d2i_ex_primitive", reason: "nested asn1 error", file: "../crypto/asn1/tasn_dec.c", line: 694 }, Error { code: 218640442, library: "asn1 encoding routines", function: "asn1_template_noexp_d2i", reason: "nested asn1 error", file: "../crypto/asn1/tasn_dec.c", line: 627, data: "Field=privateKey, Type=EC_PRIVATEKEY" }, Error { code: 269033488, library: "elliptic curve routines", function: "d2i_ECPrivateKey", reason: "EC lib", file: "../crypto/ec/ec_asn1.c", line: 899 }, Error { code: 269344910, library: "elliptic curve routines", function: "old_ec_priv_decode", reason: "decode error", file: "../crypto/ec/ec_ameth.c", line: 447 }, Error { code: 218529960, library: "asn1 encoding routines", function: "asn1_check_tlen", reason: "wrong tag", file: "../crypto/asn1/tasn_dec.c", line: 1130 }, Error { code: 218640442, library: "asn1 encoding routines", function: "asn1_template_noexp_d2i", reason: "nested asn1 error", file: "../crypto/asn1/tasn_dec.c", line: 553, data: "Field=attributes, Type=PKCS8_PRIV_KEY_INFO" }])', src/libcore/result.rs:997:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

cc @djc

Start in tests/openssl.rs by uncommenting verify_csr(&cert) in test_openssl_25519_given and running that test to reproduce the OpenSSL ASN.1 and EC_PRIVATEKEY error. Trace the verification path from there. Done means Ed25519 CSR verification succeeds without the panic and the test passes.