[jdk8u-dev] RFR: 8245543: Cgroups: Incorrect detection logic on some systems (still reproducible) [v5]

[Jonathan Dowland]

> A backport of 8245543 to jdk8u-dev for cgroups v2 support.
> 
> Not clean: needed minor adjusting for 8u approach to log output.

Jonathan Dowland has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains two new commits since the last revision:

 - replace use of Optional.isEmpty
 - 8245543: Cgroups: Incorrect detection logic on some systems (still reproducible)
   
   Backport-of: 2bbf8a2a964a64d88298a3dd184459af506e58ed

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Changes:
  - all: https://git.openjdk.org/jdk8u-dev/pull/159/files
  - new: https://git.openjdk.org/jdk8u-dev/pull/159/files/86a169cc..0b56b96c

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=159&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=159&range=03-04

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/159.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/159/head:pull/159

PR: https://git.openjdk.org/jdk8u-dev/pull/159