[crac] RFR: Extract crac functionality into OS-agnostic files [v4]

[Roman Marchenko]

On Tue, 20 Jun 2023 09:29:56 GMT, Roman Marchenko <rmarchenko at openjdk.org> wrote:

>> CRaC-related functionality is moved to `crac*.hpp/cpp` files, and now it is in `crac` class instead of `os`.
>
> Roman Marchenko has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:
> 
>   Merge branch 'crac' into crac-extract

@jankratochvil Hi, could you review this regarding your recent changes, please?

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PR Comment: https://git.openjdk.org/crac/pull/84#issuecomment-1609866337