RFR: 8301337: Remove unused os::_polling_page

[Coleen Phillimore]

On Mon, 30 Jan 2023 09:52:27 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> Hi, please consider removing the unused field _polling_page in os.
> 
> Built tested many platforms + t1.

Good + trivial, the SA doesn't refer to this data.

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Marked as reviewed by coleenp (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12287