lightningd: don't hand around partially-assembled channel_info.

wallet_commit_channel would fill in the old_remote_per_commit and
fee_states, which is weird since the caller doesn't care.

Make the caller set all the channel_info fields, so wallet_commit_channel
is a simple consumer.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/dual_open_control.c

@@ -654,7 +654,7 @@ wallet_commit_channel(struct lightningd *ld,
 		      struct amount_sat total_funding,
 		      struct amount_sat our_funding,
 		      u8 channel_flags,
-		      struct channel_info *channel_info,
+		      const struct channel_info *channel_info,
 		      u32 feerate,
 		      enum side opener,
 		      const u8 *our_upfront_shutdown_script,
@@ -678,9 +678,6 @@ wallet_commit_channel(struct lightningd *ld,
 		return NULL;
 	}
 
-	/* old_remote_per_commit not valid yet, copy valid one. */
-	channel_info->old_remote_per_commit = channel_info->remote_per_commit;
-
 	/* BOLT-7b04b1461739c5036add61782d58ac490842d98b #9
 	 * | 222/223 | `option_dual_fund`
 	 * | Use v2 of channel open, enables dual funding
@@ -816,6 +813,9 @@ static void accepter_commit_received(struct subd *dualopend,
 		goto failed;
 	}
 
+	/* old_remote_per_commit not valid yet, copy valid one. */
+	channel_info.old_remote_per_commit = channel_info.remote_per_commit;
+
 	payload->rcvd->channel =
 		wallet_commit_channel(ld, uc,
 				      &cid,

lightningd/opening_control.c

@@ -376,6 +376,9 @@ static void opening_funder_finished(struct subd *openingd, const u8 *resp,
 	/* Saved with channel to disk */
 	derive_channel_id(&cid, &funding_txid, funding_txout);
 
+	/* old_remote_per_commit not valid yet, copy valid one. */
+	channel_info.old_remote_per_commit = channel_info.remote_per_commit;
+
 	/* Steals fields from uc */
 	channel = wallet_commit_channel(ld, fc->uc,
 					&cid,
@@ -481,6 +484,9 @@ static void opening_fundee_finished(struct subd *openingd,
 
 	derive_channel_id(&cid, &funding_txid, funding_outnum);
 
+	/* old_remote_per_commit not valid yet, copy valid one. */
+	channel_info.old_remote_per_commit = channel_info.remote_per_commit;
+
 	/* Consumes uc */
 	channel = wallet_commit_channel(ld, uc,
 					&cid,