t/prereq.t labels on all tests
Revert LibList to a working state

Recent work on Liblist has resulted in an endless stream of fixes and fixes upon those fixes and fixes upon fixes upon those fixes.

* The only additional tests are testing garbage-in garbage out, not something useful.
* They are reporting spurious warnings to the end-users about said garbage
* I currently broken, and has been broken for other reasons before

I'm reverting it to the latest state that was known to be working without issues.