GTP_Templates: add decoder/encoder functions for RIM_Routing_Address_GTPC

When forwarding RAN TRANSPARENT CONTAINERs containers on GTP-C, the
sender adds a RIM ROUTING ADDRESS and a RIM ROUTING ADDRESS
DISCRIMINATOR. The RIM ROUTING ADDRESS is represented as an
octet-string, so we need encoder/decoder functions for it.

Related: OS#6095
Change-Id: I45d1f5b019f3847fd611c38dc19d78d6fe027c5a
diff --git a/library/GTP_Templates.ttcn b/library/GTP_Templates.ttcn
index f6fda36..ebd9142 100644
--- a/library/GTP_Templates.ttcn
+++ b/library/GTP_Templates.ttcn
@@ -1082,6 +1082,10 @@
 		 number_of_SI_PSI := int2bit(si_psi_num, 7),
 		 sI_PSI := si_psi
 	}
+	external function enc_RIM_Routing_Address_GTPC(in RIM_Routing_Address_GTPC ra) return octetstring
+		with { extension "prototype(convert) encode(RAW)" };
+	external function dec_PCUIF_pch_dt(in octetstring stream) return RIM_Routing_Address_GTPC
+		with { extension "prototype(convert) decode(RAW)" };
 
 	/* RAN_Information_Request */
 	template (value) RAN_Information_Request_RIM_Container_GTPC