Issue #12871: sched_get_priority_(min|max) might not be defined even though
<sched.h> is available (most notably on OpenBSD when built without pthread):
add an explicit configure check.
diff --git a/pyconfig.h.in b/pyconfig.h.in
index bf9e7fe..edc2e69 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -653,6 +653,9 @@
/* Define to 1 if you have the `round' function. */
#undef HAVE_ROUND
+/* Define to 1 if you have the `sched_get_priority_max' function. */
+#undef HAVE_SCHED_GET_PRIORITY_MAX
+
/* Define to 1 if you have the <sched.h> header file. */
#undef HAVE_SCHED_H