[4.1] d01f76a Revive the backend_conn counter

[Federico G. Schwindt]

commit d01f76a45e9674480955f93b711c409b89b91af5
Author: Dag Haavi Finstad <daghf at varnish-software.com>
Date:   Tue Mar 8 19:27:36 2016 +0100

    Revive the backend_conn counter
    
    Discussed with Federico.
    
    Fixes: #1725

diff --git a/bin/varnishd/cache/cache_backend_tcp.c b/bin/varnishd/cache/cache_backend_tcp.c
index 13a026c..9f28d22 100644
--- a/bin/varnishd/cache/cache_backend_tcp.c
+++ b/bin/varnishd/cache/cache_backend_tcp.c
@@ -382,7 +382,9 @@ VBT_Get(struct tcp_pool *tp, double tmo, const struct backend *be,
 		Lck_Lock(&tp->mtx);
 		tp->n_used--;		// Nope, didn't work after all.
 		Lck_Unlock(&tp->mtx);
-	}
+	} else
+		VSC_C_main->backend_conn++;
+
 	return (vbc);
 }