RFR: 8292286: Convert PlaceholderTable to ResourceHashtable [v3]

[Ioi Lam]

On Mon, 15 Aug 2022 18:19:41 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> This change converts the PlaceholderTable to ResourceHashtable.  It's much like the ResolutionErrorTable conversion.  This change has been performance tested with the previous set of testing with no regression.  It's also been tested tier1-3 and 4-7 with the other tables in my patch queue.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Ioi comments.

LGTM

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Marked as reviewed by iklam (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9854