[6.0] 4e50978ee Add missing VTCP_Close()

[Dridi Boukelmoune]

commit 4e50978ee356a48714d17d5ec332d10748dada06
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Wed Jun 13 10:02:28 2018 +0000

    Add missing VTCP_Close()

diff --git a/bin/varnishd/cache/cache_backend_probe.c b/bin/varnishd/cache/cache_backend_probe.c
index 3f3a106ba..4945b8efd 100644
--- a/bin/varnishd/cache/cache_backend_probe.c
+++ b/bin/varnishd/cache/cache_backend_probe.c
@@ -322,6 +322,7 @@ vbp_poke(struct vbp_target *vt)
 
 	if (proxy_header < 0) {
 		bprintf(vt->resp_buf, "%s", "No backend");
+		VTCP_close(&s);
 		return;
 	}