bpo-39026: Fix Python.h when building with Xcode (GH-29488) (GH-29732)

Fix Python.h to build C extensions with Xcode: remove a relative
include from Include/cpython/pystate.h.

(cherry picked from commit 4ae26b9c1d0c33e3db92c6f305293f9240dea358)
3 files changed