RFR: 8352181: Shenandoah: Evacuate thread roots after early cleanup

[William Kemper]

Moving the evacuation of thread roots after early cleanup allows Shenandoah to recycle immediate garbage a bit sooner in the cycle.

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Commit messages:
 - Merge remote-tracking branch 'jdk/master' into investigate-root-evacuation
 - What happens if we evacuate roots after weak roots and class unloading?

Changes: https://git.openjdk.org/jdk/pull/24090/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24090&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8352181
  Stats: 8 lines in 1 file changed: 3 ins; 5 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/24090.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24090/head:pull/24090

PR: https://git.openjdk.org/jdk/pull/24090