Remove two sneaky log_debug

src/config/config.cpp

@@ -37,7 +37,7 @@ void Config::set(const std::string& option, const std::string& value, bool save)
     }
 }
 
-void Config::connect(t_config_changed_callback callback)
+void Config::connect(const t_config_changed_callback& callback)
 {
     Config::callbacks.push_back(callback);
 }

src/config/config.hpp

@@ -54,7 +54,7 @@ public:
    * configuration change occurs (when set() is called, or when the initial
    * conf is read)
    */
-  static void connect(t_config_changed_callback);
+  static void connect(const t_config_changed_callback&);
   /**
    * Destroy the instance, forcing it to be recreated (with potentially
    * different parameters) the next time it’s needed.