[Dovecot] Dovecot won't build against recent version of GnuTLS

Hi all,

Dovecot won't build against recent versions of GnuTLS. The problem starts on line 34 of src/master/ssl-init-gnutls.c, where Dovecot generates DH params using gnutls_dh_params_generate(), a function which no longer exists [replaced with gnutls_dh_params_generate2()].

I'd fix it myself, but the signature of the function has changed to take gnutls_dh_params_t rather than prime & generator, and I'm not keen on hacking SSL code unless I really understand what's going on. It looks like the code goes on to save & free those values.

I'm tracking HG and am happy to test any changes. Appreciate it if someone with more knowledge of GnuTLS and perhaps this code in particular could take a look.

Thanks, J