Add a test for HTTP/0.9 deprecation

bin/varnishtest/tests/b00047.vtc

+varnishtest "Check that all but HTTP/1.0 and HTTP/1.1 get 400"
+
+server s1 {
+	rxreq
+	txresp -body "FOO"
+} -start
+
+varnish v1 -vcl+backend {
+} -start
+
+client c1 {
+	send "GET /\r\n\r\n"
+	rxresp
+	expect resp.status == 400
+} -run
+
+client c1 {
+	send "GET / HTTP/0.5\r\n\r\n"
+	rxresp
+	expect resp.status == 400
+} -run
+
+client c1 {
+	send "GET / HTTP/1.2\r\n\r\n"
+	rxresp
+	expect resp.status == 400
+} -run
+
+client c1 {
+	send "GET / HTTP/2.0\r\n\r\n"
+	rxresp
+	expect resp.status == 400
+} -run