[jdk21u-dev] RFR: 8326446: The User and System of jdk.CPULoad on Apple M1 are inaccurate

[Long Yang]

Hi, all

Could I have a review of this backport.

This pull request contains a backport of commit [8dbd4b391f7deb1a46a5f07f0bc46f23d6715ddb](https://github.com/openjdk/jdk/commit/8dbd4b391f7deb1a46a5f07f0bc46f23d6715ddb) from the [openjdk/jdk](https://github.com/openjdk/jdk) repository.

Testing: I ran test/jdk/jdk/jfr/event/os/TestCPULoad.java and passed. All GHA tests are passed (except linux-cross-compile, build(riscv64), Create sysroot. It looks like there's an issue with the GHA's process).

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Commit messages:
 - 8326446: The User and System of jdk.CPULoad on Apple M1 are inaccurate

Changes: https://git.openjdk.org/jdk21u-dev/pull/341/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=341&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8326446
  Stats: 30 lines in 1 file changed: 1 ins; 7 del; 22 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/341.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/341/head:pull/341

PR: https://git.openjdk.org/jdk21u-dev/pull/341