gnutls: updated to 3.7.3

Version 3.7.3 (released 2022-01-17)

** libgnutls: The allowlisting configuration mode has been added to the system-wide
   settings. In this mode, all the algorithms are initially marked as insecure
   or disabled, while the applications can re-enable them either through the
   [overrides] section of the configuration file or the new API.

** The build infrastructure no longer depends on GNU AutoGen for generating
   command-line option handling, template file parsing in certtool, and
   documentation generation. This change also removes run-time or
   bundled dependency on the libopts library, and requires Python 3.6 or later
   to regenerate the distribution tarball.

   Note that this brings in known backward incompatibility in command-line
   tools, such as long options are now case sensitive, while previously they
   were treated in a case insensitive manner: for example --RSA is no longer a
   valid option of certtool. The existing scripts using GnuTLS tools may need
   adjustment for this change.

** libgnutls: The tpm2-tss-engine compatible private blobs can be loaded and
   used as a gnutls_privkey_t. The code was originally written for the
   OpenConnect VPN project by David Woodhouse. To generate such blobs, use the
   tpm2tss-genkey tool from tpm2-tss-engine:
   https://github.com/tpm2-software/tpm2-tss-engine/#rsa-operations
   or the tpm2_encodeobject tool from unreleased tpm2-tools.

** libgnutls: The library now transparently enables Linux KTLS
   (kernel TLS) when the feature is compiled in with --enable-ktls configuration
   option. If the KTLS initialization fails it automatically falls back
   to the user space implementation.

** certtool: The certtool command can now read the Certificate Transparency
   (RFC 6962) SCT extension.  New API functions are also provided to
   access and manipulate the extension values.

** certtool: The certtool command can now generate, manipulate, and evaluate
   x25519 and x448 public keys, private keys, and certificates.

** libgnutls: Disabling a hashing algorithm through "insecure-hash"
   configuration directive now also disables TLS ciphersuites that use it as a
   PRF algorithm.

** libgnutls: PKCS#12 files are now created with modern algorithms by default.
   Previously certtool used PKCS12-3DES-SHA1 for key derivation and
   HMAC-SHA1 as an integity measure in PKCS#12.  Now it uses AES-128-CBC with
   PBKDF2 and SHA-256 for both key derivation and MAC algorithms, and the
   default PBKDF2 iteration count has been increased to 600000.

** libgnutls: PKCS#12 keys derived using GOST algorithm now uses
   HMAC_GOSTR3411_2012_512 instead of HMAC_GOSTR3411_2012_256 for integrity, to
   conform with the latest TC-26 requirements.

** libgnutls: The library now provides a means to report the status of approved
   cryptographic operations. To adhere to the FIPS140-3 IG 2.4.C., this
   complements the existing mechanism to prohibit the use of unapproved
   algorithms by making the library unusable state.

** gnutls-cli: The gnutls-cli command now provides a --list-config option to
   print the library configuration.

** libgnutls: Fixed possible race condition in
   gnutls_x509_trust_list_verify_crt2 when a single trust list object is shared
   among multiple threads. [GNUTLS-SA-2022-01-17, CVSS: low]

** API and ABI modifications:
GNUTLS_PRIVKEY_FLAG_RSA_PSS_FIXED_SALT_LENGTH: new flag in gnutls_privkey_flags_t
GNUTLS_VERIFY_RSA_PSS_FIXED_SALT_LENGTH: new flag in gnutls_certificate_verify_flags
gnutls_ecc_curve_set_enabled: Added.
gnutls_sign_set_secure: Added.
gnutls_sign_set_secure_for_certs: Added.
gnutls_digest_set_secure: Added.
gnutls_protocol_set_enabled: Added.
gnutls_fips140_context_init: New function
gnutls_fips140_context_deinit: New function
gnutls_fips140_push_context: New function
gnutls_fips140_pop_context: New function
gnutls_fips140_get_operation_state: New function
gnutls_fips140_operation_state_t: New enum
gnutls_transport_is_ktls_enabled: New function
gnutls_get_library_configuration: New function


(adam)