RFR: 8377665: JFR: Symbol table not setup for early class unloading [v2]

[Joel Sikström]

> Hello,
> 
> We observe a crash when running a major GC very early, which unloads classes, calling into JFR which is not properly set up for class unloading this early. A simple fix for this is to move the creation of the symbol table to the early setup of JFR, which allows us to successfully call `JfrCheckpointManager::on_unloading_classes()`.
> 
> Testing:
>  * Crash reproducer no longer crashes
>  * Running through Oracle's tier1-4

Joel Sikström has updated the pull request incrementally with one additional commit since the last revision:

  Markus _initial_type_set feedback

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29672/files
  - new: https://git.openjdk.org/jdk/pull/29672/files/b1d5650f..788a3c40

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29672&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29672&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/29672.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29672/head:pull/29672

PR: https://git.openjdk.org/jdk/pull/29672