Cygwin: mkdir: use correct default permissions filtered by umask

Cygwin: mkdir: use correct default permissions filtered by umask

Older coreutils created directories with mode bits filtered through
umask.  Newer coreutils creates directories with full permissions,
0777 by default.

This new coreutils behaviour uncovered the fact that default ACEs for
newly created directories were not filtered by umask starting with
commit bc444e5aa4ca.

Fix it by applying umask on the default ACEs.

Fixes: bc444e5aa4ca ("Reapply POSIX ACL change.")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>