bug#50507: New function in Emacs GnuTLS implementation

[Mattias Engdegård]

After e9983b1b63, the build of master fails on emba.gnu.org which perhaps uses 
a slightly older gnutls. Errors below.

CC       gnutls.o
gnutls.c: In function 'key_file2_aux':
gnutls.c:1829:8: error: 'GNUTLS_PKCS_PBES2_GOST_TC26Z' undeclared (first use in 
this function)
  rv |= GNUTLS_PKCS_PBES2_GOST_TC26Z;
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
gnutls.c:1829:8: note: each undeclared identifier is reported only once for 
each function it appears in
gnutls.c:1831:8: error: 'GNUTLS_PKCS_PBES2_GOST_CPA' undeclared (first use in 
this function)
  rv |= GNUTLS_PKCS_PBES2_GOST_CPA;
        ^~~~~~~~~~~~~~~~~~~~~~~~~~
gnutls.c:1833:8: error: 'GNUTLS_PKCS_PBES2_GOST_CPB' undeclared (first use in 
this function)
  rv |= GNUTLS_PKCS_PBES2_GOST_CPB;
        ^~~~~~~~~~~~~~~~~~~~~~~~~~
gnutls.c:1835:8: error: 'GNUTLS_PKCS_PBES2_GOST_CPC' undeclared (first use in 
this function)
  rv |= GNUTLS_PKCS_PBES2_GOST_CPC;
        ^~~~~~~~~~~~~~~~~~~~~~~~~~
gnutls.c:1837:8: error: 'GNUTLS_PKCS_PBES2_GOST_CPD' undeclared (first use in 
this function)
  rv |= GNUTLS_PKCS_PBES2_GOST_CPD;
        ^~~~~~~~~~~~~~~~~~~~~~~~~~