properly receive BSSMAP Clear Complete and Iu Release Complete

When sending a BSSMAP Clear or Iu Release, do not immediately discard the conn,
but wait until a BSSMAP Clear Complete / Iu Release Complete has been received.

Hence we will no longer show in the log that an incoming Release/Clear Complete
belongs to an unknown subscriber, but will still be around to properly log the
release.

Related: OS#3122
Change-Id: Ie4c6aaba3866d6e5b98004e8870a215e8cf8ffc1
diff --git a/include/osmocom/msc/gsm_data.h b/include/osmocom/msc/gsm_data.h
index 4cfe08d..c5e7aaf 100644
--- a/include/osmocom/msc/gsm_data.h
+++ b/include/osmocom/msc/gsm_data.h
@@ -148,6 +148,7 @@
 	struct {
 		struct ranap_ue_conn_ctx *ue_ctx;
 		uint8_t rab_id;
+		bool waiting_for_release_complete;
 	} iu;
 
 	struct {
@@ -164,6 +165,8 @@
 		 * to reference the SCCP connection that is
 		 * associated with this subscriber connection */
 		uint32_t conn_id;
+
+		bool waiting_for_clear_complete;
 	} a;
 };