The two test scripts actually assumed some *NIX paradigms, so we need
to adapt them so that they can work on Windows as well, the changes are
namely:
-Call the glib-mkenums and glib-genmarshal Python scripts with the
Python interpreter, not just relying on shebang lines, on Windows.
This is because the native Windows console (cmd.exe) does not support
shebang lines, for subprocess.run().
-Use NamedTemporaryFile with delete=False, otherwise Windows cannot find
the temp files we need when running the tests.
-Use universal_newlines=True for subprocess.run() so that we do not need
to worry out line ending differences on different systems.
-Make sure we are not in the temp directories we create, where the tests
are being run, upon cleanup. Windows does not like deleting
directories that we are currently in.