gnutls: updated to 3.8.4

Version 3.8.4 (released 2024-03-18)

** libgnutls: RSA-OAEP encryption scheme is now supported
  To use it with an unrestricted RSA private key, one would need to
  initialize a gnutls_x509_spki_t object with necessary parameters
  for RSA-OAEP and attach it to the private key. It is also possible
  to import restricted private keys if they are stored in PKCS#8
  format.

** libgnutls: Fix side-channel in the deterministic ECDSA.
  [GNUTLS-SA-2023-12-04, CVSS: medium] [CVE-2024-28834]

** libgnutls: Fixed a bug where certtool crashed when verifying a certificate
  chain with more than 16 certificates.
  [GNUTLS-SA-2024-01-23, CVSS: medium] [CVE-2024-28835]

** libgnutls: Compression libraries are now loaded dynamically as needed
  instead of all being loaded during gnutls library initialization.
  As a result, the library initialization should be faster.

** build: The gnutls library can now be linked with the static library
  of GMP.  Note that in order for this to work libgmp.a needs to be
  compiled with -fPIC and libhogweed in Nettle also has to be linked
  to the static library of GMP.  This can be used to prevent custom
  memory allocators from being overriden by other applications.

(adam)