[jdk8u-dev] RFR: 8239785: Cgroups: Incorrect detection logic on old systems in hotspot [v6]

[Jonathan Dowland]

> This is a backport of add18914fb1294999877b563c734a25b4c17b922 for cgroups v2 support injdk8u-dev, via the 11u backport.
> 
> It does not apply clean:
> 
>  * context issues for changes made for the different approach for logging in 8u
>  * copyright lines
> 
> Small amount of re-working of new code that used `log_trace`/`log_debug` to use the 8u approach.

Jonathan Dowland has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Update file path in comment
 - Severin's test fixes. Thanks!

-------------

Changes:
  - all: https://git.openjdk.org/jdk8u-dev/pull/135/files
  - new: https://git.openjdk.org/jdk8u-dev/pull/135/files/e4a44241..953e2d21

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=135&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=135&range=04-05

  Stats: 71 lines in 4 files changed: 50 ins; 4 del; 17 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/135.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/135/head:pull/135

PR: https://git.openjdk.org/jdk8u-dev/pull/135