RFR: 8259845: Move placeholder implementation details to cpp file and add logging [v2]

[David Holmes]

On Fri, 22 Jan 2021 21:53:01 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> See CR for details.
>> Tested with tier1-3 and manually by looking at the output.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Make 'log' inline.

Looks good.

Thanks,
David

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/2204