Please, do not use ABSPATH at all

Hello!

In my typical setup, I use WordPress in its own subdirectory `/wp`, what is normally defined in ABSPATH.
And have `content` (what is called wp-content by default) living on the same level.

```
docroot
⌞ content
⌞ cache
⌞ wp-cache-config.php
⌞ advanced-cache.php
⌞ ...
⌞ wp
⌞ wp-config.php
⌞ ...
```

If you [do more with ABSPATH](https://github.com/Automattic/wp-super-cache/search?q=ABSPATH&unscoped_q=ABSPATH), than only including default wp stuff, things are getting wired (for me).

I'm looking for the reasons of a "not working" *wp-super-cache* for hours now. From permissions, to users, and the only thing, that gave me a hint in this directions was the wrongly created path/URL to the log file. The Link in the plugins Debug Tab looks like this:

https://domain.tld/the/complete/server/root/abspath/that/conatins/domain.tld/content/cache/view_ceac38cc2a9edb4d4228ea94fd935b9d.php

Is there any chance you could use something more flexibel for the pathes,