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/Include/frameobject.h

@@ -1,12 +1,8 @@
-
-/* Frame object interface */
-
 #ifndef Py_LIMITED_API
 #ifndef Py_FRAMEOBJECT_H
 #define Py_FRAMEOBJECT_H
-#ifdef __cplusplus
-extern "C" {
-#endif
+COSMOPOLITAN_C_START_
+/* clang-format off */
 
 typedef struct {
     int b_type;                 /* what kind of block this is */
@@ -88,8 +84,6 @@ PyAPI_FUNC(void) _PyFrame_DebugMallocStats(FILE *out);
 /* Return the line of code the frame is currently executing. */
 PyAPI_FUNC(int) PyFrame_GetLineNumber(PyFrameObject *);
 
-#ifdef __cplusplus
-}
-#endif
+COSMOPOLITAN_C_END_
 #endif /* !Py_FRAMEOBJECT_H */
 #endif /* Py_LIMITED_API */