add test z00001.vtc

src/tests/z00001.vtc

+varnishtest "vcl.use and .discard"
+
+server s1 {
+} -start
+
+varnish v1 -vcl+backend {
+	import backend_dyn from "${vmod_topbuild}/src/.libs/libvmod_backend_dyn.so";
+} -start
+
+varnish v1 -vcl+backend {
+} 
+
+varnish v1 -cli "vcl.list"
+varnish v1 -cli "vcl.use vcl1"
+
+varnish v1 -cli "vcl.use vcl2"
+varnish v1 -cli "vcl.use vcl1"
+
+varnish v1 -cli "vcl.show vcl1"
+varnish v1 -cli "vcl.use vcl2"
+varnish v1 -cli "vcl.discard vcl1"
+varnish v1 -cli "vcl.list"