This test is for unix sockets open in DGRAM mode.
Server opens a socket, binds it and waits for a signal.
Client connects to the socket and sends a message.

After the signal server checks that data is readable,
and that it's still possible to connect to the bound
socket.
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>