[4.1] c656231 Missing include prompted by -std=c99

[Lasse Karstensen]

commit c656231c7c4355783f803f6825c0e515dc58acef
Author: Federico G. Schwindt <fgsch at lodoss.net>
Date:   Mon Feb 8 09:19:29 2016 +0000

    Missing include prompted by -std=c99

diff --git a/lib/libvarnishapi/vsl_query.c b/lib/libvarnishapi/vsl_query.c
index 1741c13..0159429 100644
--- a/lib/libvarnishapi/vsl_query.c
+++ b/lib/libvarnishapi/vsl_query.c
@@ -34,6 +34,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 #include <unistd.h>
 
 #include "vdef.h"