[DCCP]: Initial feature negotiation implementation

Still needs more work, but boots and doesn't crashes, even
does some negotiation!

18:38:52.174934  127.0.0.1.43458 > 127.0.0.1.5001: request <change_l ack_ratio 2, change_r ccid 2, change_l ccid 2>
18:38:52.218526  127.0.0.1.5001 > 127.0.0.1.43458: response <nop, nop, change_l ack_ratio 2, confirm_r ccid 2 2, confirm_l ccid 2 2, confirm_r ack_ratio 2>
18:38:52.185398  127.0.0.1.43458 > 127.0.0.1.5001: <nop, confirm_r ack_ratio 2, ack_vector0 0x00, elapsed_time 212>

:-)

Signed-off-by: Andrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/output.c b/net/dccp/output.c
index efd7ffb..0cc2bcf 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -64,6 +64,10 @@
 		case DCCP_PKT_DATAACK:
 			break;
 
+		case DCCP_PKT_REQUEST:
+			set_ack = 0;
+			/* fall through */
+
 		case DCCP_PKT_SYNC:
 		case DCCP_PKT_SYNCACK:
 			ackno = dcb->dccpd_seq;