[6.0] 1c9aeaae8 We don't need stdlib.h unless we compile the code

[Dridi Boukelmoune]

commit 1c9aeaae89a66521878b7cceeabbd2d98dd7e2a5
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Wed Aug 22 06:59:51 2018 +0000

    We don't need stdlib.h unless we compile the code

diff --git a/bin/varnishd/waiter/cache_waiter_epoll.c b/bin/varnishd/waiter/cache_waiter_epoll.c
index c48b72396..d0a4c690d 100644
--- a/bin/varnishd/waiter/cache_waiter_epoll.c
+++ b/bin/varnishd/waiter/cache_waiter_epoll.c
@@ -33,10 +33,10 @@
 //lint -e{766}
 #include "config.h"
 
-#include <stdlib.h>
-
 #if defined(HAVE_EPOLL_CTL)
 
+#include <stdlib.h>
+
 #include <sys/epoll.h>
 
 #include <errno.h>