channel-state: add two new states, for dualopend

v2 channel opens are going to happen over in dualopend. In order
to make sure that these don't end up in the wrong place/to keep track of
the difference between "waiting for sigs" and "have merely initiatlized
a channel", we add two new states to the channel state machine.

A channel that 'originates' in dualopend will only ever arrive at
channeld in the state CHANNELD_NORMAL.

lightningd/channel_state.h

@@ -31,9 +31,17 @@ enum channel_state {
 	ONCHAIN,
 
 	/* Final state after we have fully settled on-chain */
-	CLOSED
+	CLOSED,
+
+	/* For dual-funded channels, we start at a different state.
+	 * We transition to 'awaiting lockin' after sigs have
+	 * been exchanged */
+	DUALOPEND_OPEN_INIT,
+
+	/* Dual-funded channel, waiting for lock-in */
+	DUALOPEND_AWAITING_LOCKIN,
 };
-#define CHANNEL_STATE_MAX CLOSED
+#define CHANNEL_STATE_MAX DUALOPEND_AWAITING_LOCKIN
 
 enum state_change {
 	/* Anything other than the reasons below. Should not happen. */

lightningd/peer_control.c

@@ -1021,6 +1021,10 @@ peer_connected_hook_cb(struct peer_connected_hook_payload *payload STEALS,
 						"Awaiting unilateral close");
 			goto send_error;
 		}
+		case DUALOPEND_OPEN_INIT:
+		case DUALOPEND_AWAITING_LOCKIN:
+			/* FIXME: open dualopend */
+			abort();
 
 		case CHANNELD_AWAITING_LOCKIN:
 		case CHANNELD_NORMAL: