fetcher: Add option to retrieve response code from a fetcher

src/libstrongswan/fetcher/fetcher.h

@@ -81,6 +81,12 @@ enum fetcher_option_t {
 	 */
 	FETCH_TIMEOUT,
 
+	/**
+	 * Sets a pointer to a variable that receives the request's response code.
+	 * Additional argument is a u_int*.
+	 */
+	FETCH_RESPONSE_CODE,
+
 	/**
 	 * Callback to invoke with each chunk of data.
 	 * Additional argument fetch_callback_t.