[jdk21u-dev] RFR: 8319439: Move BufferNode from PtrQueue files to new files

[Goetz Lindenmaier]

I would like to bacvkport this change to make future 
backports easier.

It is low risk, so this is feasible although it does not fix
a bug. It is a pure move of code to a new file. The code is unchanged.
At most, it might slightly affect the size of libjvm.so.

I had to do some resolkves. 
Especially the moved code differes. 
So I moved the classes by hand. 
They differ because 
8314276: Improve PtrQueue API around size/capacity
8309899: Rename PtrQueueSet::buffer_size()
are not in 21.
The latter would be a candidate for backport as well, 
it should have low risk. But resolving against 
function names is not as annoying as applying
the changes in other files. 
What do you think?

Resolved files in detail:

src/hotspot/share/gc/g1/g1YoungGCPostEvacuateTasks.cpp
src/hotspot/share/gc/g1/jvmFlagConstraintsG1.cpp
Resolved includes.

src/hotspot/share/gc/shared/ptrQueue.cpp
src/hotspot/share/gc/shared/ptrQueue.hpp
>From these files, I copied the deleted content to
the two new files.
I verified that the original change copies these
without changing them as well.

test/hotspot/gtest/gc/shared/test_bufferNodeAllocator.cpp
Trivial resolve.

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

Commit messages:
 - Resolved files.
 - Backport 1e76ba0cd0de38da6fc2b8147627496ee2f2837b

Changes: https://git.openjdk.org/jdk21u-dev/pull/1458/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1458&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319439
  Stats: 311 lines in 17 files changed: 185 ins; 118 del; 8 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1458.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1458/head:pull/1458

PR: https://git.openjdk.org/jdk21u-dev/pull/1458