jsonrpc: Added nested messages for the getroute reply

The `route_hop` struct introduced in the previous refactoring is
reused when returning the reply to a `getroute` request. Since these
are nested messages I added the serialization and deserialization
methods.

lightningd/gossip_msg.c

@@ -25,3 +25,17 @@ void towire_gossip_getnodes_entry(u8 **pptr, const struct gossip_getnodes_entry
 	}
 	towire_u16(pptr, entry->port);
 }
+
+void fromwire_route_hop(const u8 **pptr, size_t *max, struct route_hop *entry)
+{
+	fromwire_pubkey(pptr, max, &entry->nodeid);
+	entry->amount = fromwire_u32(pptr, max);
+	entry->delay = fromwire_u32(pptr, max);
+}
+void towire_route_hop(u8 **pptr, const struct route_hop *entry)
+{
+	towire_pubkey(pptr, &entry->nodeid);
+	towire_u32(pptr, entry->amount);
+	towire_u32(pptr, entry->delay);
+}
+

lightningd/gossip_msg.h

@@ -2,6 +2,7 @@
 #define LIGHTNING_LIGHTNINGD_GOSSIP_MSG_H
 #include "config.h"
 #include <bitcoin/pubkey.h>
+#include <daemon/routing.h>
 
 struct gossip_getnodes_entry {
 	struct pubkey nodeid;
@@ -12,4 +13,7 @@ struct gossip_getnodes_entry {
 void fromwire_gossip_getnodes_entry(const tal_t *ctx, const u8 **pptr, size_t *max, struct gossip_getnodes_entry *entry);
 void towire_gossip_getnodes_entry(u8 **pptr, const struct gossip_getnodes_entry *entry);
 
+void fromwire_route_hop(const u8 **pprt, size_t *max, struct route_hop *entry);
+void towire_route_hop(u8 **pprt, const struct route_hop *entry);
+
 #endif /* LIGHTNING_LIGHTGNINGD_GOSSIP_MSG_H */