ss: fix autobound filter

Fixes following error. We currently provide garbage data to kernel, that
can abort the validation process or produce unexpected results.

$ ss -a autobound
State      Recv-Q Send-Q      Local Address:Port          Peer Address:Port
TCPDIAG answers: Invalid argument

After patch:

$ misc/ss -a autobound
State      Recv-Q Send-Q      Local Address:Port          Peer Address:Port
LISTEN     0      128                     *:44624                    *:*
ESTAB      0      0            192.168.1.21:47141        74.125.79.109:imaps
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

misc/ss.c

@@ -803,7 +803,7 @@ static int ssfilter_bytecompile(struct ssfilter *f, char **bytecode)
 	{
 		if (!(*bytecode=malloc(4))) abort();
 		((struct inet_diag_bc_op*)*bytecode)[0] = (struct inet_diag_bc_op){ INET_DIAG_BC_AUTO, 4, 8 };
-		return 8;
+		return 4;
 	}
 		case SSF_DCOND:
 		case SSF_SCOND: