RFR: JDK-8298255: JFR provide information about dynamization of number of compiler threads [v2]

[Matthias Baesken]

> The JVM supports both dynamic GC threads, and dynamic Compiler threads.
> While the GCConfiguration JFR event (see https://sap.github.io/SapMachine/jfrevents/#gcconfiguration ) seems to have at least some info about dynamization of GC threads ( field usesDynamicGCThreads), the JIT CompilerConfiguration event seems to miss this info (about JIT compiler threads dynamization), this should be added; currently the impression is given that the number is static but this is often not the case.
> As an extension, the dynamization process of adding / removing threads could be added as well to the JFR events but I am not sure if this is desired so I just started with a very simple patch.

Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:

  event field names must not be longer than 32 chars

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/11563/files
  - new: https://git.openjdk.org/jdk/pull/11563/files/42ff5021..a7bc2ce3

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=11563&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=11563&range=00-01

  Stats: 7 lines in 4 files changed: 0 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/11563.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11563/head:pull/11563

PR: https://git.openjdk.org/jdk/pull/11563