Use new-style CHECK_TYPE to avoid modifying confdefs.h. Include sys/types.h
Fixes #636431.
diff --git a/pyconfig.h.in b/pyconfig.h.in
index a6f7e83..e612494 100644
--- a/pyconfig.h.in
+++ b/pyconfig.h.in
@@ -842,7 +842,7 @@
 /* Define to `unsigned' if <sys/types.h> does not define. */
 #undef size_t
 
-/* Define to `int' if <sys/types.h> does not define. */
+/* Define to `int' if <sys/socket.h> does not define. */
 #undef socklen_t
 
 /* Define to `int' if <sys/types.h> doesn't define. */