closes bpo-39619 Fix os.chroot on HP-UX 11.31 (GH-18495)


Setting `-D_XOPEN_SOURCE=700` on HP-UX causes system functions such as chroot to be undefined.  This change stops `_XOPEN_SOURCE` begin set on HP-UX

Co-authored-by: Benjamin Peterson <benjamin@python.org>
(cherry picked from commit a9edf44a2de9b23a1690b36cdfeed7b41ab763bd)

Co-authored-by: Ian Norton <inorton@gmail.com>
3 files changed