Hide common_sockaddr_t as it needs to be removed but it's causing issues now

As mentioned in https://reviews.imfreedom.org/r/14/ this is my current fix for the `common_sockaddr_t` problem. And that is to just hide. By hiding it, we make the core network api and bonjour uses of it independent which means we can swap the out individually with smaller review requests.

Hide common_sockaddr_t as it needs to be removed but it's causing issues now

Reviewed at https://reviews.imfreedom.org/r/15/