Use suggested workaround for PyOS_CheckStack causing failure of test_[s]re.py
on Win64.

This closes bug http://sourceforge.net/bugs/?func=detailbug&group_id=5470&bug_id=116516
diff --git a/Include/pythonrun.h b/Include/pythonrun.h
index e8f4f96..b963a06 100644
--- a/Include/pythonrun.h
+++ b/Include/pythonrun.h
@@ -88,7 +88,7 @@
    to a 8k margin. */
 #define PYOS_STACK_MARGIN 2048
 
-#if defined(WIN32) && defined(_MSC_VER)
+#if defined(WIN32) && !defined(MS_WIN64) && defined(_MSC_VER)
 /* Enable stack checking under Microsoft C */
 #define USE_STACKCHECK
 #endif