Avoid double-free of DNS directors

The director is freed in vcc_backend.c already, so don't free it in
vcc_dir_dns.c too.

Fixes: #863

lib/libvcl/vcc_dir_dns.c

@@ -368,5 +368,4 @@ vcc_ParseDnsDirector(struct vcc *tl)
 	Fc(tl, 0, "\t.ttl = %f", ttl);
 	Fc(tl, 0, ",\n");
 	Fc(tl, 0, "};\n");
-	Ff(tl, 0, "\tVRT_fini_dir(cli, VGCDIR(_%.*s));\n", PF(tl->t_dir));
 }