Implement PEP 393.
diff --git a/Include/pyport.h b/Include/pyport.h
index 5309de6..3239020 100644
--- a/Include/pyport.h
+++ b/Include/pyport.h
@@ -286,12 +286,15 @@
/* fastest possible local call under MSVC */
#define Py_LOCAL(type) static type __fastcall
#define Py_LOCAL_INLINE(type) static __inline type __fastcall
+#define Py_LOCAL_CALLBACK(name) (__fastcall *name)
#elif defined(USE_INLINE)
#define Py_LOCAL(type) static type
#define Py_LOCAL_INLINE(type) static inline type
+#define Py_LOCAL_CALLBACK(name) (*name)
#else
#define Py_LOCAL(type) static type
#define Py_LOCAL_INLINE(type) static type
+#define Py_LOCAL_CALLBACK(name) (*name)
#endif
/* Py_MEMCPY can be used instead of memcpy in cases where the copied blocks