Update nghttp2_session.c

Add missing free call on error in inflight_settings_new().

lib/nghttp2_session.c

@@ -682,6 +682,7 @@ static int inflight_settings_new(nghttp2_inflight_settings **settings_ptr,
   if (niv > 0) {
     (*settings_ptr)->iv = nghttp2_frame_iv_copy(iv, niv, mem);
     if (!(*settings_ptr)->iv) {
+      nghttp2_mem_free(mem, *settings_ptr);
       return NGHTTP2_ERR_NOMEM;
     }
   } else {