xquartz: Remove a check for NSAppKitVersionNumber >= NSAppKitVersionNumber10_7

This check is always true on our supported systems.

Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
(cherry picked from commit 5ae47a9d579e8cb0fbe938455faea53ed75d7098)
3 jobs for server-1.20-branch in 5 minutes and 28 seconds (queued for 2 seconds)