[lworld] RFR: 8294462: [lworld] set system property valhalla.enableValhalla when -XX:+EnableValhalla [v2]

[Mandy Chung]

On Tue, 27 Sep 2022 15:04:22 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> Updated to set the system property after all of the option setting locations have been processed.
>> Verified via -XshowSettings.
>
> Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove extra blank line

We need an internal API to test if `-XX:+EnableValhalla` and `-XX:+EnablePrimitiveClass` flags are set.   Instead of using a system property, it may be time to add a method in `jdk.internal.value.PrimitiveClass` or other class to ask the VM if the flag is enabled.

A side note: `-XX:+EnableValhalla` will ultimately become `--enable-preview` and the internal API `jdk.internal.misc.PreviewFeatures::isEnabled` already exists.

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PR: https://git.openjdk.org/valhalla/pull/769