asyncio: sync overlapped.c with GitHub

On Python 3.3, use aliases:

* PyMem_RawMalloc = PyMem_Malloc
* PyMem_RawFree = PyMem_Free

These aliases are not need in Python 3.5, but this change makes synchronization
of code base simpler.

Modules/overlapped.c

@@ -23,6 +23,12 @@
 #  define T_POINTER T_ULONGLONG
 #endif
 
+/* Compatibility with Python 3.3 */
+#if PY_VERSION_HEX < 0x03040000
+#    define PyMem_RawMalloc PyMem_Malloc
+#    define PyMem_RawFree PyMem_Free
+#endif
+
 #define F_HANDLE F_POINTER
 #define F_ULONG_PTR F_POINTER
 #define F_DWORD "k"