8320761: [Lilliput] Implement compact identity hashcode

[rkennke]

WIP

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Integration blocker

 ⚠️ Dependency #191 must be integrated first

Issue

• JDK-8320761: [Lilliput] Implement compact identity hashcode (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/lilliput.git pull/192/head:pull/192
$ git checkout pull/192

Update a local copy of the PR:
$ git checkout pull/192
$ git pull https://git.openjdk.org/lilliput.git pull/192/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 192

View PR using the GUI difftool:
$ git pr show -t 192

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/lilliput/pull/192.diff

[bridgekeeper]

👋 Welcome back rkennke! A progress list of the required criteria for merging this PR into pr/191 will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.