RFR: 8373262: Parallel: gc/metaspace/CompressedClassSpaceSizeInJmapHeap.java fails [v2]

[Albert Mingkun Yang]

> [JDK-8367541](https://bugs.openjdk.org/browse/JDK-8367541) changes the fields in `src/hotspot/share/gc/parallel/parallelScavengeHeap.hpp` to be non-static. The corresponding access in `src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/parallel/ParallelScavengeHeap.java` should be updated as well.
> 
> `TEST=gc/metaspace/CompressedClassSpaceSizeInJmapHeap.java JTREG_JAVA_OPTIONS=-XX:+UseParallelGC` fails consistently without the fix and passes with the fix.
> 
> Test: tier1-2

Albert Mingkun Yang has updated the pull request incrementally with one additional commit since the last revision:

  review

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Changes:
  - all: https://git.openjdk.org/jdk/pull/28700/files
  - new: https://git.openjdk.org/jdk/pull/28700/files/67c306e4..1f70f90b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28700&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28700&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/28700.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28700/head:pull/28700

PR: https://git.openjdk.org/jdk/pull/28700