tests: Mark tests that fail on NetBSD as expected failures.

tests: Mark tests that fail on NetBSD as expected failures.

* modules/dup3-tests (Depends-on): Add test-xfail.
(Makefile.am): Expect that test-dup3 fails on NetBSD.
* modules/fdutimensat-tests (Depends-on): Add test-xfail.
(Makefile.am): Expect that test-fdutimensat fails on NetBSD.
* modules/futimens-tests (Depends-on): Add test-xfail.
(Makefile.am): Expect that test-futimens fails on NetBSD.
* modules/utimens-tests (Depends-on): Add test-xfail.
(Makefile.am): Expect that test-utimens fails on NetBSD.
* modules/utimensat-tests (Depends-on): Add test-xfail.
(Makefile.am): Expect that test-utimensat fails on NetBSD.