git: openjdk/loom: fibers: Lots of cleanup. Better comments on why some tests are failing. Comment out some tests that are no longer failing. Added some tests that are failing but not already in the list.

[duke]

Changeset: aa46c1b6
Author:    Chris Plummer <chris.plummer at oracle.com>
Date:      2021-08-31 06:15:23 +0000
URL:       https://git.openjdk.java.net/loom/commit/aa46c1b63c57ae5e95053c6653e0c24ac782545d

Lots of cleanup. Better comments on why some tests are failing. Comment out some tests that are no longer failing. Added some tests that are failing but not already in the list.

! test/hotspot/jtreg/ProblemList-vthread.txt