Fix Windows build

Author: vstinner

Python/ceval.c

@@ -494,7 +494,7 @@ get_stack(uintptr_t *start, size_t *size)
     SetThreadStackGuarantee(&guarantee);
 
     *start = (uintptr_t)low + guarantee;
-    *size = (uintptr_t)high - start;
+    *size = (uintptr_t)high - *start;
 
 #elif defined(__APPLE__)
     pthread_t this_thread = pthread_self();