[MEDIUM] stats: don't use s->ana_state anymore

The stats handler used to store internal states in s->ana_state. Now
we only rely on si->st0 in which we can store as many states as we
have possible outputs. This cleans up the stats code a lot and makes
it more maintainable. It has also reduced code size by a few hundred
bytes.
diff --git a/src/proto_uxst.c b/src/proto_uxst.c
index 5c4ac4d..41ae9c6 100644
--- a/src/proto_uxst.c
+++ b/src/proto_uxst.c
@@ -471,7 +471,8 @@
 
 		stream_int_register_handler(&s->si[1], stats_io_handler);
 		s->si[1].private = s;
-		s->si[1].st0 = s->si[1].st1 = 0;
+		s->si[1].st1 = 0;
+		s->si[1].st0 = STAT_CLI_INIT;
 
 		s->srv = s->prev_srv = s->srv_conn = NULL;
 		s->pend_pos = NULL;