gbproxy: Introduce TC_overload

When the SGSN is sending an OVERLOAD message, we expect that to
propagate down to every BSS on the other side.

Change-Id: Ic61fabd9c633bcb3f256fe7aa5834e66cc66a4fb
diff --git a/library/Osmocom_Gb_Types.ttcn b/library/Osmocom_Gb_Types.ttcn
index a345d7f..2afedcc 100644
--- a/library/Osmocom_Gb_Types.ttcn
+++ b/library/Osmocom_Gb_Types.ttcn
@@ -2077,6 +2077,38 @@
 		}
 	}
 
+	/* 10.4.36 */
+	template (value) PDU_BSSGP
+	ts_OVERLOAD(template (value) BIT1 priority_class) := {
+		pDU_BSSGP_OVERLOAD := {
+			bssgpPduType := '42'O,
+			priority_Class_Indicator := {
+				iEI := '8f'O,
+				ext := '1'B,
+				lengthIndicator := {
+					length1 := 1
+				},
+				priority_Class_Indicator_Value := priority_class,
+				spare := '0000000'B
+			}
+		}
+	}
+	template (present) PDU_BSSGP
+	tr_OVERLOAD(template (present) BIT1 priority_class) := {
+		pDU_BSSGP_OVERLOAD := {
+			bssgpPduType := '42'O,
+			priority_Class_Indicator := {
+				iEI := '8f'O,
+				ext := '1'B,
+				lengthIndicator := {
+					length1 := 1
+				},
+				priority_Class_Indicator_Value := priority_class,
+				spare := '0000000'B
+			}
+		}
+	}
+
 	/* PDU permitted on PTP BVC only (TS 48.018 Section 5.4.1) */
 	template (present) PDU_BSSGP tr_BSSGP_PERMITTED_PTP_ONLY := (
 		{pDU_BSSGP_DL_UNITDATA := ?},