permute_tx: don't save permutation map.

We no longer need it anywhere.  This simplifies things to the point where
we might as well just not include dust outputs as we go, rather than
explicitly removing them, which gets rid of remove_dust.c as well.

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

daemon/peer.h

@@ -52,8 +52,6 @@ struct commit_info {
 	struct channel_state *cstate;
 	/* Other side's signature for last commit tx (if known) */
 	struct bitcoin_signature *sig;
-	/* Map for permutation: see commit_tx.c */
-	int *map;
 };
 
 struct peer_visible_state {