The enfoce_gzip constant, and the other in the same group in your config, actually refer to how wordpress should serve admin side related JS and CSS, and it seems like you are interested in the front end.
Setting gzip compression is something that you should do in your server configuration level (several options depending on the server, but for apache you will probably do it in the .htaccess file), the reason is that most files being served – CSS, JS, images, do not pass though wordpress code at all and therefor wordpress can not have any influence on how they are being served.