RFR: 8364203: Ignore native mac tests on headless [v2]

[Kevin Rushforth]

On Tue, 29 Jul 2025 07:12:52 GMT, Johan Vos <jvos at openjdk.org> wrote:

>> Add PlatformUtil.isHeadless() method.
>> Use that in tests to conditionally skip tests.
>> 
>> Fix JDK-8364203
>
> Johan Vos has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Exclude setup/teardown in case of headless platform

LGTM. I verified that the test is still run normally and skipped when running headless glass.

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Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1859#pullrequestreview-3067273998