gnutls: Update to 3.6.16

gnutls: Update to 3.6.16

- Update from 3.6.14 to 3.6.16
- Update rootfile
- Changelog
   * Version 3.6.16 (released 2021-05-24)
     ** libgnutls: Fixed potential miscalculation of ECDSA/EdDSA code backported from
        Nettle.  In GnuTLS, as long as it is built and linked against the fixed
        version of Nettle, this only affects GOST curves.  [CVE-2021-20305]
     ** libgnutls: Fixed potential use-after-free in sending "key_share"
        and "pre_shared_key" extensions. When sending those extensions, the
        client may dereference a pointer no longer valid after
        realloc. This happens only when the client sends a large Client
        Hello message, e.g., when HRR is sent in a resumed session
        previously negotiated large FFDHE parameters, because the initial
        allocation of the buffer is large enough without having to call
        realloc (#1151).  [GNUTLS-SA-2021-03-10, CVSS: low]
   * Version 3.6.15 (released 2020-09-04)
     ** libgnutls: Fixed "no_renegotiation" alert handling at incorrect timing.
        The server sending a "no_renegotiation" alert in an unexpected timing,
        followed by an invalid second handshake was able to cause a TLS 1.3 client to
        crash via a null-pointer dereference. The crash happens in the application's
        error handling path, where the gnutls_deinit function is called after
        detecting a handshake failure (#1071).  [GNUTLS-SA-2020-09-04, CVSS: medium]
     ** libgnutls: If FIPS self-tests are failed, gnutls_fips140_mode_enabled() now
        indicates that with a false return value (!1306).
     ** libgnutls: Under FIPS mode, the generated ECDH/DH public keys are checked
        accordingly to SP800-56A rev 3 (!1295, !1299).
     ** libgnutls: gnutls_x509_crt_export2() now returns 0 upon success, rather than
        the size of the internal base64 blob (#1025). The new behavior aligns to the
        existing documentation.
     ** libgnutls: Certificate verification failue due to OCSP must-stapling is not
        honered is now correctly marked with the GNUTLS_CERT_INVALID flag
        (!1317). The new behavior aligns to the existing documentation.
     ** libgnutls: The audit log message for weak hashes is no longer printed twice
        (!1301).
     ** libgnutls: Fixed version negotiation when TLS 1.3 is enabled and TLS 1.2 is
        disabled in the priority string. Previously, even when TLS 1.2 is explicitly
        disabled with "-VERS-TLS1.2", the server still offered TLS 1.2 if TLS 1.3 is
        enabled (#1054).

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>