[PATCH v2] secur32: Fix compile error on older gnutls.

[Hans Leidekker]

On Thu, 2019-02-07 at 23:41 +0000, Alistair Leslie-Hughes wrote:
> +static int (*pgnutls_privkey_import_rsa_raw)(gnutls_privkey_t, const gnutls_datum_t *,
> +                                        const gnutls_datum_t *, const gnutls_datum_t *,
> +                                        const gnutls_datum_t *, const gnutls_datum_t *,
> +                                        const gnutls_datum_t *, const gnutls_datum_t *,
> +                                        const gnutls_datum_t *);
> +

What version of GnuTLS is that? It would be nice to have a comment
stating the version that makes the function available, like we have for
the other functions that aren't available everywhere.