As it turns out, we have examples of internal functions called
type_name_get_private() in the wild (especially among older libraries),
so we need to use a name for the per-instance private data getter
function that hopefully won't conflict with anything.
Add two new methods to GProxyAddress for recovering information about
the destination URI that the proxy was created for (and modify
GProxyAddressEnumerator to set that information when creating the
GProxyAddress).
A GSocketInetAddress representing the proxy server address with additional
properties proxy type, destination address and port, username and password.
Reviewed-by: Dan Winship <danw@gnome.org>
