Disable TLS 1.1 with gnutls by default as it is causing problems

[Troels Liebe Bentsen]

By default gnutls tries with TLS 1.1, but most servers only support TLS 1.0, most will handle fall-back to this version gracefully, but a lot won't.

Also TLS 1.0 is still the default for almost all browsers even if TLS 1.1 and 1.2 is supported. Fx. in IE on vista and Windows 7 both are disabled unless you edit the registry, Firefox and Chrome also only tries TLS 1.0. So having subversion being the only application defaulting to TLS 1.1 might not be the best idea.

GnuTLS bug with more details:
https://savannah.gnu.org/support/?107372

Patch to disable TLS 1.1 by default:

diff --git a/src/ne_socket.c b/src/ne_socket.c
index 31e96f1..efa1086 100644
--- a/src/ne_socket.c
+++ b/src/ne_socket.c
@@ -1646,7 +1646,7 @@ int ne_sock_accept_ssl(ne_socket *sock, ne_ssl_context *ctx)
 #elif defined(HAVE_GNUTLS)
     gnutls_init(&ssl, GNUTLS_SERVER);
     gnutls_credentials_set(ssl, GNUTLS_CRD_CERTIFICATE, ctx->cred);
- gnutls_set_default_priority(ssl);
+ gnutls_priority_set_direct (ssl, "NORMAL:-VERS-TLS1.1", NULL);

     /* Set up dummy session cache. */
     gnutls_db_set_store_function(ssl, store_sess);
@@ -1726,7 +1726,7 @@ int ne_sock_connect_ssl(ne_socket *sock, ne_ssl_context *ctx, void *userdata)
 #elif defined(HAVE_GNUTLS)
     /* DH and RSA params are set in ne_ssl_context_create */
     gnutls_init(&sock->ssl, GNUTLS_CLIENT);
- gnutls_set_default_priority(sock->ssl);
+ gnutls_priority_set_direct (sock->ssl, "NORMAL:-VERS-TLS1.1", NULL);
     gnutls_session_set_ptr(sock->ssl, userdata);
     gnutls_credentials_set(sock->ssl, GNUTLS_CRD_CERTIFICATE, ctx->cred);