Fix a spurious segfault on Windows.

This can be seen, e.g., when running regression_tests.pd gui-less in
Windows, as our CI script does. The easy fix is to just bypass the gui
finalization code in glob_quit() when running gui-less (sys_nogui).
6 jobs for windows-segfault-fix in 229 minutes and 4 seconds (queued for 3 seconds)
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