python38: fix build on macOS

Python 3.8 fails to build on macOS for two reasons:

* python-3.x-distutils-C++.patch fails to apply cleanly.
* An #include for <util.h> is missing, causing a build failure:

    ./Modules/posixmodule.c:6586:9: error: implicit declaration of function 'openpty' is invalid in C99
        if (openpty(&master_fd, &slave_fd, NULL, NULL, NULL) != 0)
            ^

Use the correct version of python-3.x-distutils-C++.patch, and add a
patch to #include <util.h>.