Fill Last Used E-UTRAN PLMN Id when in CSFB

Since recently, osmo-bsc behaves strictly as per specs, meaning it will
only send the "Cell selection indicator after release of all TCH and SDCCH IE"
in RR Channel Release iff:
* "Last Used E-UTRAN PLMN Id" was received in the CommonID sent MSC->BSC
* "Last Used E-UTRAN PLMN Id" was received insider "old BSS to new BSS Information"
  in the HandoverRequest sent MSC->BSC.
On the other hand, CSFB_Indicator from ClearCommand MSC->BSC is nw
ignored and not taken into account.

Hence, let's update osmo-msc to also behave correctly by sending the
Last Used E-UTRAN PLMN ID at CommonID tx time to avoid regressions in
CSFB support when running against newer osmo-bsc.

Let's keep sending the CSFB Indicator in ClearCommand as we used too, in
order to keep compatibility with older BSCs (as per spec).

Related: SYS#5337
Change-Id: Ic5f175b179973d0a50d94f00e15f5a3e332605fc
diff --git a/include/osmocom/msc/vlr_sgs.h b/include/osmocom/msc/vlr_sgs.h
index fa9d948..1a4984d 100644
--- a/include/osmocom/msc/vlr_sgs.h
+++ b/include/osmocom/msc/vlr_sgs.h
@@ -97,7 +97,7 @@
 int vlr_sgs_loc_update(struct vlr_instance *vlr, struct vlr_sgs_cfg *cfg,
 		       vlr_sgs_lu_response_cb_t response_cb, vlr_sgs_lu_paging_cb_t paging_cb,
 		       vlr_sgs_lu_mminfo_cb_t mminfo_cb, char *mme_name, enum vlr_lu_type type, const char *imsi,
-		       struct osmo_location_area_id *new_lai);
+		       struct osmo_location_area_id *new_lai, struct osmo_plmn_id *last_eutran_plmn);
 void vlr_sgs_loc_update_acc_sent(struct vlr_subscr *vsub);
 void vlr_sgs_loc_update_rej_sent(struct vlr_subscr *vsub);
 void vlr_sgs_detach(struct vlr_instance *vlr, const char *imsi, bool eps);