RFR: 8342818: Implement CPU Time Profiling for JFR [v26]

[Johannes Bechberger]

> This is the code for the [JEP draft: CPU Time based profiling for JFR].

Johannes Bechberger has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 152 commits:

 - Merge remote-tracking branch 'origin' into parttimenerd_jfr_cpu_time_sampler4
 - Compute actual sampling period via si_overrun
 - Making queue processing only stoppable in debug builds
 - Obtain minimal period via the CONFIG_HZ parameter of the kernel
 - Improve Throttling test case
 - Make parsing rates safer
 - Fix ActiveSetting event for CPUTimeSamples
 - Don't walk continuations in signal handler
 - Added more comments around queue implementation
 - Don't treat stackTrace attribute specially for CPUTimeSamples
 - ... and 142 more: https://git.openjdk.org/jdk/compare/3eece6e9...f7f8de0b

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Changes: https://git.openjdk.org/jdk/pull/20752/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20752&range=25
  Stats: 2624 lines in 52 files changed: 2419 ins; 176 del; 29 mod
  Patch: https://git.openjdk.org/jdk/pull/20752.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20752/head:pull/20752

PR: https://git.openjdk.org/jdk/pull/20752