RFR: 8309756: Occasional crashes with pipewire screen capture on Wayland

[Phil Race]

I'd like to backport the fix for this crash to the JDK 21 stabilisation repo.
The fix is in code that is only used by AWT Robot on Wayland desktops so is quite isolated and unlikely to affect anything else.

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Commit messages:
 - Backport d3d0dbc36369da0c17a66f8b633e73a150ab8c4f

Changes: https://git.openjdk.org/jdk21/pull/25/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21&pr=25&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309756
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21/pull/25.diff
  Fetch: git fetch https://git.openjdk.org/jdk21.git pull/25/head:pull/25

PR: https://git.openjdk.org/jdk21/pull/25