splice: Resume splice_locked on reestablish

A new case where `splice_locked` must be sent again on reestablish.

This handles the case where `splice_locked` did not complete locally or remotely and must be resumed.

Author: ddustin

channeld/channeld.c

@@ -5177,6 +5177,13 @@ static void peer_reconnect(struct peer *peer,
 						  true,
 						  false,
 						  true);
+		} else if (inflight->is_locked
+			   && bitcoin_txid_eq(remote_next_funding,
+					      &inflight->outpoint.txid)) {
+			status_info("Splice is not confirmed but locked on"
+				    " chain -- resending splice_locked");
+			peer_write(peer->pps,
+				   take(towire_splice_locked(NULL, &peer->channel_id)));
 		} else if (bitcoin_txid_eq(remote_next_funding,
 					   &inflight->outpoint.txid)) {
 			/* Don't send sigs unless we have theirs */