When 'make check' is run on Cygwin and Emacs has been built with native
compilation, all the tests in comp-tests.el and benchmark-tests.el fail
with fork errors, for the reasons explained in etc/PROBLEMS.  I don't
see an easy way to fix this by rebasing, as is done elsewhere in the
code, and I don't think it's worth investing any effort into this just
for the sake of making some tests pass.  I propose that we just skip
these tests.

Patch attached (with a placeholder for the bug number).  OK for emacs-29?

Ken