REORG: include: move arg.h to haproxy/arg{,-t}.h

Almost no change was needed; chunk.h was replaced with buf-t.h.
It dpeends on types/vars.h and types/protocol_buffers.h.
diff --git a/src/stick_table.c b/src/stick_table.c
index 8ceafa3..c2e1e85 100644
--- a/src/stick_table.c
+++ b/src/stick_table.c
@@ -29,7 +29,7 @@
 #include <types/global.h>
 #include <types/stats.h>
 
-#include <proto/arg.h>
+#include <haproxy/arg.h>
 #include <proto/cli.h>
 #include <proto/http_rules.h>
 #include <proto/log.h>