Add missing <strings.h>

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2223 d4fa192b-c00b-0410-8231-f00ffab90ce4

lib/libvarnish/vsb.c

@@ -34,6 +34,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 
 #include "vsb.h"
 

lib/libvarnishcompat/strndup.c

@@ -34,6 +34,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <strings.h>
 
 #ifndef HAVE_STRLCPY
 #include "compat/strlcpy.h"