Add counters: pcu.bts.N.pch.requests.timeout

Implement T3113 for paging over PCH with default value of 7s (same as
T3113 in OsmoBSC). Increase the new counter on timeout.

Related: SYS#4878
Change-Id: I97475c3dbe2cf00b9cbfec39e93a3c65cb7f749f
diff --git a/src/bts.h b/src/bts.h
index c28bd97..5e45527 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -126,6 +126,7 @@
 	CTR_LLC_DL_BYTES,
 	CTR_LLC_UL_BYTES,
 	CTR_PCH_REQUESTS,
+	CTR_PCH_REQUESTS_TIMEDOUT,
 	CTR_RACH_REQUESTS,
 	CTR_11BIT_RACH_REQUESTS,
 	CTR_SPB_UL_FIRST_SEGMENT,
@@ -263,6 +264,9 @@
 	struct osmo_stat_item_group *statg;
 
 	struct GprsMsStorage *ms_store;
+
+	/* List of struct bts_pch_timer for active PCH pagings */
+	struct llist_head pch_timer;
 };
 
 #ifdef __cplusplus