SSL_CTX_get_extra_chain_certs() retrieves the extra chain certificates
associated with B<ctx>, or the chain associated with the current certificate
of B<ctx> if the extra chain is empty.
+The returned stack should not be freed by the caller.
SSL_CTX_get_extra_chain_certs_only() retrieves the extra chain certificates
associated with B<ctx>.
+The returned stack should not be freed by the caller.
SSL_CTX_clear_extra_chain_certs() clears all extra chain certificates
associated with B<ctx>.