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/Objects/object.c

@@ -1,12 +1,6 @@
-
-/* Generic object operations; and implementation of None */
-
-#include "Python.h"
-#include "frameobject.h"
-
-#ifdef __cplusplus
-extern "C" {
-#endif
+/* clang-format off */
+#include "third_party/python/Include/Python.h"
+#include "third_party/python/Include/frameobject.h"
 
 _Py_IDENTIFIER(Py_Repr);
 _Py_IDENTIFIER(__bytes__);
@@ -2074,7 +2068,3 @@ _Py_Dealloc(PyObject *op)
     (*Py_TYPE(op)->tp_dealloc)(op);
 }
 #endif
-
-#ifdef __cplusplus
-}
-#endif