RFR: 8342011: Conditionally compile ReservedHeapSpace compressed heap support [v3]

[Kim Barrett]

> Please review this change to ReservedHeapSpace to conditionally include the
> support for compressed oops only in 64bit builds.  This code is unused and
> inapplicable in 32bit builds.  Further, it contains code that is problematic
> in a 32bit build.  See the JBS issue for details.
> 
> Testing: mach5 tier1, GHA testing

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 four additional commits since the last revision:

 - Merge branch 'master' into conditional-compile-compressed-heap-support
 - swap cond block
 - improve conditionalization
 - disable coops setup for 32bit

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21484/files
  - new: https://git.openjdk.org/jdk/pull/21484/files/82c6846d..d9b0a011

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21484&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21484&range=01-02

  Stats: 14391 lines in 369 files changed: 11592 ins; 854 del; 1945 mod
  Patch: https://git.openjdk.org/jdk/pull/21484.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21484/head:pull/21484

PR: https://git.openjdk.org/jdk/pull/21484