MEDIUM: h1: make the parser support a pointer to a start line

This will allow the parser to fill some extra fields like the method or
status without having to store them permanently in the HTTP message. At
this point however the parser cannot restart from an interrupted read.
diff --git a/src/mux_h2.c b/src/mux_h2.c
index 546debb..4d9a7bc 100644
--- a/src/mux_h2.c
+++ b/src/mux_h2.c
@@ -3104,7 +3104,7 @@
 	 * having to realign the buffer.
 	 */
 	ret = h1_headers_to_hdr_list(b_peek(buf, ofs), b_peek(buf, ofs) + max,
-	                             list, sizeof(list)/sizeof(list[0]), h1m);
+	                             list, sizeof(list)/sizeof(list[0]), h1m, NULL);
 	if (ret <= 0) {
 		/* incomplete or invalid response, this is abnormal coming from
 		 * haproxy and may only result in a bad errorfile or bad Lua code