Issue #4258:  Use 30-bit digits for Python longs, on 64-bit platforms.
Backport of r70459.
diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index b2b3afd..4ce0536 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -123,6 +123,7 @@
 PyAPI_FUNC(void) _PyImportHooks_Init(void);
 PyAPI_FUNC(int) _PyFrame_Init(void);
 PyAPI_FUNC(int) _PyInt_Init(void);
+PyAPI_FUNC(int) _PyLong_Init(void);
 PyAPI_FUNC(void) _PyFloat_Init(void);
 PyAPI_FUNC(int) PyByteArray_Init(void);