[master] RFR: 8306122: [Lilliput] Refactor full GC forwarding [v2]

[Roman Kennke]

> Current implementation of full-GC/sliding-GC forwarding in Lilliput is problematic:
> - It's scattered and hardwired all over GC implementations
> - It's not switched by UseCompactObjectMonitors
> - The serial compaction in G1 is commented-out and not used, not even under -XX:-UseCompactObjectMonitors
> 
> This change aims to refactor the forwarding code to address these issues.
> 
> It should be functionally equivalent but provides cleaner separation of Lilliput changes. It also cleans up and greatly reduces the upstream diff. The lack of G1 serial compaction with Lilliput enabled will be addressed in a follow-up change.
> 
> Testing:
>  - [x] hotspot_gc
>  - [x] tier1
>  - [ ] tier2

Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:

  32 bit build fix

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

Changes:
  - all: https://git.openjdk.org/lilliput/pull/85/files
  - new: https://git.openjdk.org/lilliput/pull/85/files/d2c6bed7..e4a81227

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=lilliput&pr=85&range=01
 - incr: https://webrevs.openjdk.org/?repo=lilliput&pr=85&range=00-01

  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/lilliput/pull/85.diff
  Fetch: git fetch https://git.openjdk.org/lilliput.git pull/85/head:pull/85

PR: https://git.openjdk.org/lilliput/pull/85