Shutdown host sockets on internal shutdown

This is required to make the shutdown visible to peers outside the
sandbox.

The readClosed / writeClosed fields were dropped, as they were
preventing a shutdown socket from reading the remainder of queued bytes.
The host syscalls will return the appropriate errors for shutdown.

The control message tests have been split out of socket_unix.cc to make
the (few) remaining tests accessible to testing inherited host UDS,
which don't support sending control messages.

Updates #273

PiperOrigin-RevId: 251763060

0 files changed, 0 insertions, 0 deletions