updated Doxyfile

properly close all doxygen groups
fixed remaining doxygen warnings

src/libstrongswan/plugins/agent/agent_plugin.h

@@ -44,4 +44,4 @@ struct agent_plugin_t {
  */
 plugin_t *plugin_create();
 
-#endif /* AGENT_PLUGIN_H_ @}*/
+#endif /** AGENT_PLUGIN_H_ @}*/

src/libstrongswan/plugins/agent/agent_private_key.h

@@ -44,5 +44,5 @@ struct agent_private_key_t {
  */
 builder_t *agent_private_key_builder(key_type_t type);
 
-#endif /*AGENT_PRIVATE_KEY_H_ @}*/
+#endif /** AGENT_PRIVATE_KEY_H_ @}*/