Move many counters from BSC-global to per-BTS granularity

We used to have a lot of counters only globlly per BSC, but they're
much more useful on a per-BTS level.

Change-Id: I954b9dda72b83b91d46a934c221a8b3375743599
diff --git a/include/osmocom/bsc/gsm_data_shared.h b/include/osmocom/bsc/gsm_data_shared.h
index d7514ca..e762c24 100644
--- a/include/osmocom/bsc/gsm_data_shared.h
+++ b/include/osmocom/bsc/gsm_data_shared.h
@@ -807,6 +807,8 @@
 	/* PCU socket state */
 	char *pcu_sock_path;
 	struct pcu_sock_state *pcu_state;
+
+	struct rate_ctr_group *bts_ctrs;
 };