Initial handling support for RIM messages

This code doesn't do anything yet app-related with the received RIM
messages, but already provides the initial infrastructure to handle them
in the future, and does first checkings.

Related: SYS#5103
Change-Id: Ia0ade0e97ea781ec655439c008b6cefaf3e90dec
diff --git a/src/gprs_pcu.h b/src/gprs_pcu.h
index 058d102..a1cd1ed 100644
--- a/src/gprs_pcu.h
+++ b/src/gprs_pcu.h
@@ -124,6 +124,7 @@
 struct gprs_pcu *gprs_pcu_alloc(void *ctx);
 
 struct gprs_rlcmac_bts *gprs_pcu_get_bts_by_nr(struct gprs_pcu *pcu, uint8_t bts_nr);
+struct gprs_rlcmac_bts *gprs_pcu_get_bts_by_cgi_ps(struct gprs_pcu *pcu, struct osmo_cell_global_id_ps *cgi_ps);
 
 void gprs_pcu_set_initial_cs(struct gprs_pcu *pcu, uint8_t cs_dl, uint8_t cs_ul);
 void gprs_pcu_set_initial_mcs(struct gprs_pcu *pcu, uint8_t mcs_dl, uint8_t mcs_ul);