RFR: 8256401: ZGC: Improve ZList verification [v3]

[Stefan Karlsson]

On Mon, 16 Nov 2020 19:59:20 GMT, Per Liden <pliden at openjdk.org> wrote:

>> The ZList verification is currently fairly weak. I propose that we make the verification stronger to easier detect corrupt lists and misuse of list nodes. This patch also removes the unused `ZList::transfer()` function.
>
> Per Liden has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review 1

Marked as reviewed by stefank (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/1230