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/PC/launcher.c

@@ -1,3 +1,4 @@
+/* clang-format off */
 /*
  * Copyright (C) 2011-2013 Vinay Sajip.
  * Licensed to PSF under a contributor agreement.
@@ -8,11 +9,6 @@
  * Curt Hagenlocher (job management)
  */
 
-#include <windows.h>
-#include <shlobj.h>
-#include <stdio.h>
-#include <tchar.h>
-
 #define BUFSIZE 256
 #define MSGSIZE 1024