s/_alloca/alloca/g; Windows doesn't need the former, at least not unless
__STDC__ is defined (or something like that ...).
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index 28a8e28..80a3157 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1450,9 +1450,9 @@
 PyOS_CheckStack(void)
 {
 	__try {
-		/* _alloca throws a stack overflow exception if there's
+		/* alloca throws a stack overflow exception if there's
 		   not enough space left on the stack */
-		_alloca(PYOS_STACK_MARGIN * sizeof(void*));
+		alloca(PYOS_STACK_MARGIN * sizeof(void*));
 		return 0;
 	} __except (EXCEPTION_EXECUTE_HANDLER) {
 		/* just ignore all errors */