gsm/gsm0480: introduce gsm0480_create_release_complete()

In OsmoMSC, it's required to be able to specify a particular GSM 04.07
transaction ID for GSM 04.80 Release complete message instead of the
hard-coded value, that is used gsm0480_create_ussd_release_complete().

Let's finally deprecate gsm0480_create_ussd_release_complete(), and
introduce a new function without USSD prefix, as this message
is also used in other "structured" supplementary services.

Change-Id: Ie3ac85fcef90a5e532334ba3482804d5305c88d7
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 602c7a6..ae7c0a1 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -89,6 +89,8 @@
 gsm0480_create_ussd_resp;
 gsm0480_create_ussd_notify;
 gsm0480_create_ussd_release_complete;
+gsm0480_create_release_complete;
+
 gsm0480_extract_ie_by_tag;
 gsm0480_parse_facility_ie;
 gsm0480_decode_ussd_request;