Summary:
This gets the socket portability layer functional enough that most of the socket tests are passing, the few that are left are depending on specific error messages.
This also switches all of the additional overloads for some of the socket functions to forward to a single implementation, to make adjustments to these functions easier in the future. (most of the functions already needed adjustments and would have had to change regardless)

Reviewed By: yfeldblum

Differential Revision: D3814011

fbshipit-source-id: c6793ee74a91d9e164775a2d52c96f54b28b9f24