Implements tryEnableFastOpen by creating a localhost socket and enabling
the TCP_FASTOPEN socket option. On builds where TCP_FASTOPEN isn't
available, setting the socket option fails and tryEnableFastOpen returns
false.
This was verified on a supporting build (latest Windows 10) and an
unsupporting build (Windows 8.1, couldn't find an ISO for an older
Windows 10 build).
Change-Id: I497117dc2f04acdd2b0cc836e20d12d69076b939