Panic in certificate parsing in crypto/x509 and golang.org/x/crypto/cryptobyte

On 32-bit architectures, a malformed input to crypto/x509 or the ASN.1 parsing functions of golang.org/x/crypto/cryptobyte can lead to a panic.

The malformed certificate can be delivered via a crypto/tls connection to a client, or to a server that accepts client certificates. net/http clients can be made to crash by an HTTPS server, while net/http servers that accept client certificates will recover the panic and are unaffected.