BUILD: stats: define several missing structures in stats.h
channel, stream_interface, appctx, buffer, proxy and htx ones are used
in function arguments and most of them are not defined but were inherited
from intermediary inclues. Let's define them here and drop the unneeded
includes.
diff --git a/include/haproxy/stats.h b/include/haproxy/stats.h
index bdb9c07..8c3aa8d 100644
--- a/include/haproxy/stats.h
+++ b/include/haproxy/stats.h
@@ -24,11 +24,14 @@
#define _HAPROXY_STATS_H
#include <haproxy/api.h>
-#include <haproxy/applet-t.h>
#include <haproxy/stats-t.h>
-#include <haproxy/stream_interface-t.h>
-#include <haproxy/tools-t.h>
+struct stream_interface;
+struct channel;
+struct buffer;
+struct proxy;
+struct appctx;
+struct htx;
/* These two structs contains all field names and descriptions according to
* the the number of entries in "enum stat_field" and "enum info_field"