Add missing include

Add missing pthread include.

Thanks to 191919 for the heads-up.

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@4008 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishtest/vtc.h

@@ -28,6 +28,8 @@
  * $Id$
  */
 
+#include <pthread.h>
+
 struct vsb;
 struct vtclog;
 struct cmds;