Perform build and magnum tuning

Building o//third_party/python now takes 5 seconds on my PC

This change works towards modifying Python to use runtime dispatching
when appropriate. For example, when loading the magnums in the socket
module, it's a good idea to check if the magnum is zero, because that
means the local system platform doesn't support it.

third_party/python/Python/thread.c

@@ -1,28 +1,12 @@
-
+/* clang-format off */
 /* Thread package.
    This is intended to be usable independently from Python.
    The implementation for system foobar is in a file thread_foobar.h
    which is included by this file dependent on config settings.
    Stuff shared by all thread_*.h files is collected here. */
 
-#include "Python.h"
-
-#ifndef _POSIX_THREADS
-/* This means pthreads are not implemented in libc headers, hence the macro
-   not present in unistd.h. But they still can be implemented as an external
-   library (e.g. gnu pth in pthread emulation) */
-# ifdef HAVE_PTHREAD_H
-#  include <pthread.h> /* _POSIX_THREADS */
-# endif
-#endif
-
-#ifndef DONT_HAVE_STDIO_H
-#include <stdio.h>
-#endif
-
-#include <stdlib.h>
-
-#include "pythread.h"
+#include "third_party/python/Include/Python.h"
+#include "third_party/python/Include/pythread.h"
 
 #ifndef _POSIX_THREADS