[MINOR] stats: report HTTP message state and buffer flags in error dumps

Debugging parsing errors can be greatly improved if we know what the parser
state was and what the buffer flags were (especially for closed inputs/outputs
and full buffers). Let's add that to the error snapshots.
diff --git a/include/proto/proto_http.h b/include/proto/proto_http.h
index e7181ec..417d5e6 100644
--- a/include/proto/proto_http.h
+++ b/include/proto/proto_http.h
@@ -91,7 +91,7 @@
 void http_return_srv_error(struct session *s, struct stream_interface *si);
 void http_capture_bad_message(struct error_snapshot *es, struct session *s,
                               struct buffer *buf, struct http_msg *msg,
-			      struct proxy *other_end);
+			      int state, struct proxy *other_end);
 unsigned int get_ip_from_hdr2(struct http_msg *msg, const char *hname, int hlen,
 			      struct hdr_idx *idx, int occ);