[master] b7588cd include <string.h> not <strings.h>

[Poul-Henning Kamp]

commit b7588cd0d5d826351b71c52d8615b4be1faf91ad
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Sat Nov 18 17:36:48 2017 +0000

    include <string.h> not <strings.h>

diff --git a/lib/libvarnish/binary_heap.c b/lib/libvarnish/binary_heap.c
index 196ac6e..b19516c 100644
--- a/lib/libvarnish/binary_heap.c
+++ b/lib/libvarnish/binary_heap.c
@@ -456,7 +456,7 @@ binheap_reorder(const struct binheap *bh, unsigned idx)
 #ifdef TEST_DRIVER
 
 #include <stdio.h>
-#include <strings.h>
+#include <string.h>
 
 #include "vdef.h"
 #include "miniobj.h"