RFR: 8357370: Export supported GCs in JVMCI [v3]

[Doug Simon]

On Tue, 20 May 2025 13:32:08 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

>> I need a way to detect in JVMCI if Shenandoah GC is supported (that is, built-in) by HotSpot. I need it for Shenandoah, because some vendors don't build it, but for cleanliness the relevant preprocessor constants should be exported for all GCs.
>> 
>> Testing:
>>  - [x] build/test https://github.com/oracle/graal/pull/10904
>
> Roman Kennke has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Align most trailing \s

LGTM and trivial.

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Marked as reviewed by dnsimon (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25325#pullrequestreview-2854208149