If we use gnutls 2.12.0 or later it's necessary to call
gnutls_transport_set_lowat() to disable the lowat functionality. Since
this function is deprecated in new versions of gnutls, call it only if
using an older version.
g_io_gnutls_push_func);
gnutls_transport_set_pull_function(gnutls_channel->session,
g_io_gnutls_pull_func);
+#if GNUTLS_VERSION_NUMBER < 0x020c00
gnutls_transport_set_lowat(gnutls_channel->session, 0);
+#endif
gnutls_priority_set_direct(gnutls_channel->session,
"NORMAL:!VERS-TLS1.1:!VERS-TLS1.0", NULL);