Summary: fix warning

get_mem.c

@@ -1,4 +1,4 @@
-/*  $Id: get_mem.c,v 1.3 2017/02/18 21:14:12 bch Exp $
+/*  $Id: get_mem.c,v 1.4 2017/02/26 16:03:48 bch Exp $
  * Adapted: get memory usage on OpenBSD
  * Author: Christian Barthel <bch@vcs.onfire.org>
  *
@@ -14,11 +14,14 @@
 #include <sys/swap.h>
 #include <sys/mount.h>
 #include <sys/proc.h>
+
+#include <unistd.h>
+
 #include <X11/Xos.h>
 #include <X11/Intrinsic.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
+#include <err.h>
 #include "MemStripChart.h"
 
 static int pageshift = -1;