connectd: do feature bits check after init exchange.

This will help with the next patch, where we wean off using a global
for features: connectd.c has access to the feature bits.

Since connectd might now want to send a message, it needs the crypto_state
non-const, which makes this less trivial than it would otherwise be.

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

devtools/gossipwith.c

@@ -142,7 +142,7 @@ static struct io_plan *simple_read(struct io_conn *conn,
 static struct io_plan *handshake_success(struct io_conn *conn,
 					 const struct pubkey *them,
 					 const struct wireaddr_internal *addr,
-					 const struct crypto_state *orig_cs,
+					 struct crypto_state *orig_cs,
 					 char **args)
 {
 	u8 *msg;