RFR: 8349512: Duplicate PermittedSubclasses entries with doclint enabled [v2]

[Vicente Romero]

On Fri, 7 Feb 2025 18:19:51 GMT, Liam Miller-Cushon <cushon at openjdk.org> wrote:

>> This change avoids emitting duplicate `PermittedSubclasses` entries when `-Xdoclint` is enabled.
>> 
>> `-Xdoclint` causes some trees to be re-attributed, and the second attribution was resulting in permitted subclasses being added again, and those side effects were not discarded. This fix causes `addPermittedSubclass` to not insert duplicate entries.
>
> Liam Miller-Cushon has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Update @test with new bug ID

Marked as reviewed by vromero (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/23507#pullrequestreview-2602499154