bts: Add TC_pcu_rr_suspend() to test forwarding of RR SUSPEND via PCU socket

This test opens a SDCCH and sends a RR SUSPEND message from the
simulated MS.  It then expects the BTS to pick that up and forward
it to the PCU socket rather than via RSL to the BSC.

Change-Id: I4da6e9d7c5dfbd0e017d2a63c6474da700c38e52
Related: OS#2249
Related: OS#4023
diff --git a/library/PCUIF_Types.ttcn b/library/PCUIF_Types.ttcn
index 750e0b4..455082a 100644
--- a/library/PCUIF_Types.ttcn
+++ b/library/PCUIF_Types.ttcn
@@ -193,7 +193,9 @@
 	OCT4		tlli,
 	OCT6		ra_id,
 	uint8_t		cause
-} with { variant "" };
+} with {
+	variant (tlli) "BYTEORDER(last)"
+};
 
 
 type union PCUIF_MsgUnion {