MEDIUM: http: disable support for HTTP/0.9 by default

There's not much reason for continuing to accept HTTP/0.9 requests
nowadays except for manual testing. Now we disable support for these
by default, unless option accept-invalid-http-request is specified,
in which case they continue to be upgraded to 1.0.
diff --git a/src/proto_http.c b/src/proto_http.c
index a0c9e1c..606aebd 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -2939,10 +2939,6 @@
 		}
 	}
 
-	/* 4. We may have to convert HTTP/0.9 requests to HTTP/1.0 */
-	if (unlikely(msg->sl.rq.v_l == 0) && !http_upgrade_v09_to_v10(txn))
-		goto return_bad_req;
-
 	/* RFC7230#2.6 has enforced the format of the HTTP version string to be
 	 * exactly one digit "." one digit. This check may be disabled using
 	 * option accept-invalid-http-request.
@@ -2961,6 +2957,11 @@
 			goto return_bad_req;
 		}
 	}
+	else {
+		/* 4. We may have to convert HTTP/0.9 requests to HTTP/1.0 */
+		if (unlikely(msg->sl.rq.v_l == 0) && !http_upgrade_v09_to_v10(txn))
+			goto return_bad_req;
+	}
 
 	/* ... and check if the request is HTTP/1.1 or above */
 	if ((msg->sl.rq.v_l == 8) &&