 Eg. in an application's config file that gets processed through  * ENGINE_ctrl_cmd_string(). If this returns zero, it is not available to  * ENGINE_ctrl_cmd_string(), only ENGINE_ctrl(). */ int ENGINE_cmd_is_executable(ENGINE *e, int cmd);  /* This function works like ENGINE_ctrl() with the exception of taking a  * command name instead of a command number, and can handle optional 