[jdk8u-dev] RFR: 8245543: Cgroups: Incorrect detection logic on some systems (still reproducible) [v6]

[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 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 73 additional commits since the last revision:

 - replace use of Optional.isEmpty
 - 8245543: Cgroups: Incorrect detection logic on some systems (still reproducible)
   
   Backport-of: 2bbf8a2a964a64d88298a3dd184459af506e58ed
 - Severin's test fixes. Thanks!
 - Replace log_warning with tty->print_cr
 - 8253435: Cgroup: 'stomping of _mount_path' crash if manually mounted cpusets exist
   
   Backport-of: 0054c15f60cce6470be05d29bfacbdb74cfb7bc9
 - 8252359: HotSpot Not Identifying it is Running in a Container
   
   Backport-of: 76f0588aaf265439a589cceb924e3ea9d3fda8f1
 - replace log_trace with tty->print_cr
 - 8278951: containers/cgroup/PlainRead.java fails on Ubuntu 21.10
   
   Reviewed-by: sgehwolf
   Backport-of: 35172cdaf38d83cd3ed57a5436bf985dde2d802b
 - PlainRead: ProcessBuilder: jdk8u-appropriate command line flags
 - adjust jtreg settings and imports for 8u
 - ... and 63 more: https://git.openjdk.org/jdk8u-dev/compare/0b56b96c...e4e93116

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

Changes:
  - all: https://git.openjdk.org/jdk8u-dev/pull/159/files
  - new: https://git.openjdk.org/jdk8u-dev/pull/159/files/0b56b96c..e4e93116

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=159&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=159&range=04-05

  Stats: 4480 lines in 127 files changed: 3197 ins; 781 del; 502 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