RFR: 8338539: New Object to ObjectMonitor mapping: riscv64 implementation [v2]

[Gui Cao]

> The riscv64 implementation of JDK-8315884 New Object to ObjectMonitor mapping
> 
> ### Testing:
> - [x] tier1-3 & hotspot:tier4 tests (release)
> - [x] test/hotspot/jtreg/runtime/Monitor/UseObjectMonitorTableTest.java (release & fastdebug)

Gui Cao 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 remote-tracking branch 'upstream/master' into JDK-8338539
 - 8338539: New Object to ObjectMonitor mapping: riscv64 implementation

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/20621/files
  - new: https://git.openjdk.org/jdk/pull/20621/files/b636586e..4ad30729

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20621&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20621&range=00-01

  Stats: 3392 lines in 65 files changed: 1657 ins; 1558 del; 177 mod
  Patch: https://git.openjdk.org/jdk/pull/20621.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20621/head:pull/20621

PR: https://git.openjdk.org/jdk/pull/20621