circpad: Don't pad if Tor is in dormant mode.

This is something we should think about harder, but we probably want dormant
mode to be more powerful than padding in case a client has been inactive for a
day or so. After all, there are probably no circuits open at this point and
dormant mode will not allow the client to open more circuits.

Furthermore, padding should not block dormant mode from being activated, since
dormant mode relies on SocksPort activity, and circuit padding does not mess
with that.

src/feature/hibernate/hibernate.h

@@ -32,6 +32,7 @@ int getinfo_helper_accounting(control_connection_t *conn,
                               const char **errmsg);
 uint64_t get_accounting_max_total(void);
 void accounting_free_all(void);
+bool accounting_tor_is_dormant(void);
 
 #ifdef HIBERNATE_PRIVATE
 /** Possible values of hibernate_state */