config/Param: split block-specific attributes to new struct ConfigBlock

The old struct config_param remains only for top-level string options.

src/input/plugins/SmbclientInputPlugin.cxx

@@ -66,14 +66,14 @@ public:
  */
 
 static InputPlugin::InitResult
-input_smbclient_init(gcc_unused const config_param &param, Error &error)
+input_smbclient_init(gcc_unused const ConfigBlock &block, Error &error)
 {
 	if (!SmbclientInit(error))
 		return InputPlugin::InitResult::UNAVAILABLE;
 
 	// TODO: create one global SMBCCTX here?
 
-	// TODO: evaluate config_param, call smbc_setOption*()
+	// TODO: evaluate ConfigBlock, call smbc_setOption*()
 
 	return InputPlugin::InitResult::SUCCESS;
 }