The buffer size return value from gnutls_dh_params_import_pkcs3(), when
specifying GNUTLS_X509_FMT_PEM, seems to include a trailing \0 byte,
after "-----END DH PARAMETERS-----<NL>". On the other hand,
gnutls_rsa_params_export_pkcs1() with GNUTLS_X509_FMT_PEM sets the
returned buffer size to not include any trailing \0, after "-----END RSA
PRIVATE KEY-----<NL>".
That's the behavior I've observed with 2.0.4; and I haven't yet built
2.4.0. If that's the case, I'm not really sure if it's a major issue,
but perhaps this should be noted in the man pages.