When shutting down helper processes, PosixSocketHelper::close() in
SocketWindows when trying to close the socket fd with
WSANOTINITIALISED. This was due to us initiating WinSock2 during static
initialization and presumably also not terminating WinSock2 properly.
Similar to WinSock2 initiation, calling CRT during static
initialization is considered dangerous given the CRT DLL itself may not
yet be initialized.
Because of the above, we move to perform this Windows-specific
runtime setup/teardown calls into the main() functions.
