PATCH: fix warning on systems without TCP_KEEPxxx

[Federico G. Schwindt]

Hi,

  Just a reminder. Not all OS support TCP_KEEPxxx, OpenBSD being one of them.

  f.-

diff --git a/bin/varnishd/cache/cache_acceptor.c b/bin/varnishd/cache/cache_acceptor.c
index 6a601a8..3138f9f 100644
--- a/bin/varnishd/cache/cache_acceptor.c
+++ b/bin/varnishd/cache/cache_acceptor.c
@@ -387,7 +387,9 @@ vca_acct(void *arg)
 {
 	struct listen_sock *ls;
 	double t0, now;
+#ifdef HAVE_TCP_KEEP
 	unsigned u;
+#endif
 	int i;
 
 	THR_SetName("cache-acceptor");