[master] RFR: Replace stack-locking with fast-locking [v2]

[Roman Kennke]

> I'd like to integrate the changes from the corresponding upstream PR into Lilliput upfront. This allows to get some testing in context of Lilliput, and also allows to work on follow-up changes, e.g. eliminate a lot of the load-klass stuff, improve hash-code, and simplification in GCs (especially Shenandoah and ZGC), as well as implement/enable some features in serviceability that haven't been possible because SA couldn't safely access object's Klass*.
> 
> See upstream PR for description:
> https://github.com/openjdk/jdk/pull/10590
> 
> This PR is a 1:1 mirror of the upstream change, with some additional changes that touch Lilliput parts (e.g. synchronizer.cpp and Shenandoah). The upstream PR has received an enormous amount of testing, perf testing, discussion and design reviews, etc.
> 
> Ok to go into Lilliput?
> 
> Thanks,
> Roman

Roman Kennke has updated the pull request incrementally with seven additional commits since the last revision:

 - Merge remote-tracking branch 'jdk-rkennke/fast-locking' into fast-locking3
 - Merge remote-tracking branch 'origin/fast-locking' into fast-locking
 - RISC-V port
 - Revert "Re-use r0 in call to unlock_object()"
   
   This reverts commit ebbcb615a788998596f403b47b72cf133cb9de46.
 - Merge remote-tracking branch 'origin/fast-locking' into fast-locking
 - Fix number of rt args to complete_monitor_locking_C, remove some comments
 - Re-use r0 in call to unlock_object()

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

Changes:
  - all: https://git.openjdk.org/lilliput/pull/56/files
  - new: https://git.openjdk.org/lilliput/pull/56/files/5aadb9c5..71f8cd8e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=lilliput&pr=56&range=01
 - incr: https://webrevs.openjdk.org/?repo=lilliput&pr=56&range=00-01

  Stats: 381 lines in 17 files changed: 89 ins; 222 del; 70 mod
  Patch: https://git.openjdk.org/lilliput/pull/56.diff
  Fetch: git fetch https://git.openjdk.org/lilliput pull/56/head:pull/56

PR: https://git.openjdk.org/lilliput/pull/56