Revert "Don't check ACLs in t/compare-trees on FreeBSD."

This reverts commit 985b17f45707fe3759ca13f005625934f5f63b4c.

That should have been *NetBSD*.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>
Don't check ACLs in t/compare-trees on NetBSD.

Treat NetBSD like Cygwin and Darwin (OS X) in t/compare-trees.  This
should finish the process of disabling POSIX ACL support on NetBSD
that was started here: 349ff15c7db09883abc20bdf3e8a4df6bff12cd3.

Signed-off-by: Rob Browning <rlb@defaultvalue.org>