[jdk11u-dev] RFR: 8305186: Reference.waitForReferenceProcessing should be more accessible to tests [v2]

[SendaoYan]

> Hi all,
> 
> This pull request contains a backport of commit [d8f012ea](https://github.com/openjdk/jdk/commit/d8f012ea2a0514020434d5db6047e36941e9349b) from the [openjdk/jdk](https://git.openjdk.org/jdk) repository.
> 
> The commit being backported was authored by Brent Christian on 25 Apr 2025 and was reviewed by Kim Barrett.
> 
> The github shows it's not cleanly backport, seems that this file has different context. I compare the patch file from main-line repo and jdk11u-dev repo, the change lines are all the same.
> 
> I have verified this clean backport PR locally with test test/jdk/java/lang/ref/FinalizerHistogramTest.java after apply the patch JDK-8298783 which use the newly added function.
> 
> Thanks!

SendaoYan has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:

 - Merge branch 'openjdk:master' into jbs8305186
 - Revert change of supportsConcurrentGCPhaseControl
 - Revert "Backport da4dd7c008da4be54ee5f58d1ac19f440fd2a74e"
   
   This reverts commit 30c94906fe8fd65ba21fe95a66ae7da7d7ca5e4a.
 - Backport d8f012ea2a0514020434d5db6047e36941e9349b
 - Backport da4dd7c008da4be54ee5f58d1ac19f440fd2a74e

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

Changes:
  - all: https://git.openjdk.org/jdk11u-dev/pull/3105/files
  - new: https://git.openjdk.org/jdk11u-dev/pull/3105/files/7709c20d..d975eab0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=3105&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=3105&range=00-01

  Stats: 7354 lines in 128 files changed: 3749 ins; 2355 del; 1250 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/3105.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/3105/head:pull/3105

PR: https://git.openjdk.org/jdk11u-dev/pull/3105