sched.h can exist without sched affinity support
diff --git a/pyconfig.h.in b/pyconfig.h.in
index e9a4cac..0544ba3 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -653,6 +653,9 @@
 /* Define to 1 if you have the <sched.h> header file. */
 #undef HAVE_SCHED_H
 
+/* Define to 1 if you have the `sched_setaffinity' function. */
+#undef HAVE_SCHED_SETAFFINITY
+
 /* Define to 1 if you have the `select' function. */
 #undef HAVE_SELECT