Disable _XOPEN_SOURCE on NetBSD 1.x.
Will backport to 2.5
diff --git a/Misc/NEWS b/Misc/NEWS
index 2017092..a0403de 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -331,6 +331,8 @@
 Build
 -----
 
+- Disable _XOPEN_SOURCE on NetBSD 1.x.
+
 - configure now checks whether gcc supports the PyArg_ParseTuple format
   attribute.