RFR: 8303485: Replacing os.name for operating system customization [v6]

[Naoto Sato]

On Fri, 24 Mar 2023 00:27:42 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> Improvements to support OS specific customization for JDK internal use:
>>  - To select values and code; allowing elimination of unused code and values
>>  - Optionally evaluated by build processes, compilation, or archiving (i.e. CDS)
>>  - Simple API to replace adhoc comparisons with `os.name`
>>  - Clear and consistent use across build, runtime, and JDK modules
>>  
>> The PR includes updates within java.base to use the new API.
>
> Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Rename OperatingSystem enum values to uppercase

LGTM

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Marked as reviewed by naoto (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/12931#pullrequestreview-1357032533