peer: correctly disable further dequeuing after DISCONNECT
peer: correctly disable further dequeuing after DISCONNECT

Once the driver has indicated that the peer sholud be disconnected,
we should flush any pending socket buffers to the kernel, but not
queue any new ones, nor allow any to be dequeud.

socket_close() does the right thing. socket_shutdown() would still
allow future messages to be dequeued (and dispatched).

Signed-off-by: Tom Gundersen <7c8224529a7c718e876cb2496c973509fde1e50e@jklm.no>

bus1/dbus-broker