[jdk16] RFR: 8260704: ParallelGC: oldgen expansion needs release-store for _end [v2]

[Kim Barrett]

> Please review this change that ensures MutableSpace::_end is updated after
> everything else that is relevant when expanding, by using a release_store to
> perform the update.  With this change the storestore that was added by
> JDK-8257999 is no longer needed.
> 
> Testing:
> mach5 tier1-3, tier5

Kim Barrett 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 two additional commits since the last revision:

 - Merge branch 'master' into move_barrier
 - Move JDK-8257999 barrier to correct location

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

Changes:
  - all: https://git.openjdk.java.net/jdk16/pull/141/files
  - new: https://git.openjdk.java.net/jdk16/pull/141/files/91d8be35..3929bb7f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk16&pr=141&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk16&pr=141&range=00-01

  Stats: 242 lines in 29 files changed: 100 ins; 112 del; 30 mod
  Patch: https://git.openjdk.java.net/jdk16/pull/141.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk16 pull/141/head:pull/141

PR: https://git.openjdk.java.net/jdk16/pull/141