DIAMETER_Emulation: Add support for IMSI in Subscription-Id

Ths IMSI on the Gx interface is encoded into a different AVP than
on the S6a/S6d interfaces.  Let's make sure our DIAMETER_Emulation
knows both formats.

Change-Id: I299fcc2e01e908914df32fda4fb93b1114402c77
diff --git a/library/DIAMETER_Templates.ttcn b/library/DIAMETER_Templates.ttcn
index 533ede2..11746eb 100644
--- a/library/DIAMETER_Templates.ttcn
+++ b/library/DIAMETER_Templates.ttcn
@@ -101,6 +101,7 @@
 };
 
 /* 3GPP TS 29.272 Section 7.1.8 */
+const uint32_t c_DIAMETER_3GPP_Gx_AID := 16777238;
 const uint32_t c_DIAMETER_3GPP_S6_AID := 16777251;
 const uint32_t c_DIAMETER_3GPP_S13_AID := 16777252;
 const uint32_t c_DIAMETER_3GPP_S7_AID := 16777308;
@@ -190,6 +191,14 @@
 	vendor_id := vendor_id_3GPP
 }
 
+template (present) GenericAVP tr_SubcrIdType(template (present) DCC_NONE_Subscription_Id_Type t) := {
+	avp := {
+		avp_header := tr_DIA_Hdr(c_AVP_Code_DCC_NONE_Subscription_Id_Type),
+		avp_data := {
+			avp_DCC_NONE_Subscription_Id_Type := t
+		}
+	}
+}
 
 template (value) GenericAVP ts_AVP_OriginHost(template (value) charstring host) := {
 	avp := {