MSC_Tests: make sgsap interface optional

At the moment the sgsap always enabled in the testsuite. This means the
testsuite will try to connect the SGs interface of osmo-msc on
initalization. If the connection fails, the testcase will fail also.

Unfortunately the related patches that add the SGs interface to osmo-msc
are not yet merged to master. This causes almost all testcases to fail,
so lets have the SGs interface as an option that we can switch on when
the SGs interface patches are merged to master.

Change-Id: I429c0c5250d4b61de8a4d6399f284ce2c87cca93
Related: OS#3645
diff --git a/msc/BSC_ConnectionHandler.ttcn b/msc/BSC_ConnectionHandler.ttcn
index 735cd21..7b88192 100644
--- a/msc/BSC_ConnectionHandler.ttcn
+++ b/msc/BSC_ConnectionHandler.ttcn
@@ -72,7 +72,8 @@
 	charstring ipa_ctrl_ip,
 	integer ipa_ctrl_port,
 	boolean ipa_ctrl_enable,
-	boolean mm_info
+	boolean mm_info,
+	boolean sgsap_enable
 };
 
 /* get a one-octet bitmaks of supported algorithms based on Classmark information */
@@ -137,8 +138,11 @@
 	activate(as_Tguard());
 	/* Route all SMPP messages for our MSISDN to us */
 	f_create_smpp_expect(hex2str(pars.msisdn));
+
 	/* Route all SGs message for our IMSI to us */
-	f_create_sgsap_expect(pars.imsi);
+	if (g_pars.sgsap_enable == true) {
+		f_create_sgsap_expect(pars.imsi);
+	}
 
 	if (g_pars.ipa_ctrl_enable == true) {
 		f_ipa_ctrl_start(g_pars.ipa_ctrl_ip, g_pars.ipa_ctrl_port);