https://github.com/a-j-wood/pv/pull/1

From: Sam James <sam@gentoo.org>
Date: Wed, 8 Sep 2021 01:03:29 +0100
Subject: [PATCH] src/pv/number.c: add missing <stddef.h> include for NULL

--- a/src/pv/number.c
+++ b/src/pv/number.c
@@ -2,6 +2,8 @@
  * Functions for converting strings to numbers.
  */
 
+#include <stddef.h>
+
 #ifdef HAVE_CONFIG_H
 #include "config.h"
 #endif
