xquartz: Ensure the mouse pointer is shown when switching to a native macOS alert or window

Fixes: https://github.com/XQuartz/XQuartz/issues/100
Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
(cherry picked from commit 4ae36f41)
3 jobs for server-1.20-branch in 7 minutes (queued for 2 seconds)
Status Job ID Name Coverage
  Docker Image
passed #9048592
debian-testing

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  Build And Test
passed #9048593
autotools-build-and-test

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passed #9048594
meson-build-and-test

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