[jdk11u-dev] RFR: 8239785: Cgroups: Incorrect detection logic on old systems in hotspot

[Jonathan Dowland]

This is a backport of 8239785 for jdk11u. It depends upon
pr/865: 8253714 (hopefully the bots will figure this out automatically)

It's not clean, but the only conflict was the copyright line in the
comment header for src/hotspot/share/prims/whitebox.hpp.

I tried these tests, and they pass:

test/hotspot/jtreg/applications/ctw/modules/java_compiler.java
test/hotspot/jtreg/compiler/c2/Test8004741.java
test/hotspot/jtreg/containers/cgroup/CgroupSubsystemFactory.java

Awaiting tier tests via GA.

---------
### Progress
- [x] Change must not contain extraneous whitespace
- [x] Commit message must refer to an issue
- [ ] Change must be properly reviewed

### Integration blocker
 ⚠️ Dependency #865 must be integrated first



### Reviewing
<details><summary>Using <code>git</code></summary>

Checkout this PR locally: \
`$ git fetch https://git.openjdk.java.net/jdk11u-dev pull/881/head:pull/881` \
`$ git checkout pull/881`

Update a local copy of the PR: \
`$ git checkout pull/881` \
`$ git pull https://git.openjdk.java.net/jdk11u-dev pull/881/head`

</details>
<details><summary>Using Skara CLI tools</summary>

Checkout this PR locally: \
`$ git pr checkout 881`

View PR using the GUI difftool: \
`$ git pr show -t 881`

</details>
<details><summary>Using diff file</summary>

Download this PR as a diff file: \
<a href="https://git.openjdk.java.net/jdk11u-dev/pull/881.diff">https://git.openjdk.java.net/jdk11u-dev/pull/881.diff</a>

</details>

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Depends on: https://git.openjdk.java.net/jdk11u-dev/pull/865

Commit messages:
 - 8239785: Cgroups: Incorrect detection logic on old systems in hotspot

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/881/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=881&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8239785
  Stats: 694 lines in 6 files changed: 526 ins; 96 del; 72 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/881.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/881/head:pull/881

PR: https://git.openjdk.java.net/jdk11u-dev/pull/881