RFR: 8265104: CpuLoad and SystemCpuLoad in OperatingSystem MXBean returns -1.0 [v2]

[Yasumasa Suenaga]

> I got -1.0 from both CpuLoad and SystemCpuLoad in OperatingSystem MXBean when I run the application on Fedora 33 x64 which is installed cgroups V2.
> 
> ![jconsole-cpuload](https://user-images.githubusercontent.com/7421132/114485721-6372a180-9c47-11eb-81d9-568324cba336.png)
> 
> I do not run the application in the container, nor do not run with resource limitation on cgroups, so JMX should report CPU load on host value in this case.

Yasumasa Suenaga has updated the pull request incrementally with one additional commit since the last revision:

  Return host CPU load directly from getCpuLoad()

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/3447/files
  - new: https://git.openjdk.java.net/jdk/pull/3447/files/f01564f3..8123fb36

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3447&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3447&range=00-01

  Stats: 7 lines in 1 file changed: 4 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3447.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3447/head:pull/3447

PR: https://git.openjdk.java.net/jdk/pull/3447