mncc: Support IPv6 addresses (new version mncc 7)

Apparently commit 06b859ca314f53a902329ed95848dbafef1d4f87 forgot to
bump the MNCC_SOCK_VERSION field from 5 to 6.

Change-Id: I5448ff931ec33f24f4837a51376f1703fe97683b
diff --git a/msc/MSC_Tests.ttcn b/msc/MSC_Tests.ttcn
index fb2a46e..5129c5b 100644
--- a/msc/MSC_Tests.ttcn
+++ b/msc/MSC_Tests.ttcn
@@ -1979,6 +1979,7 @@
 	cpars.mgw_conn_1.mgw_rtp_ip := "::1";
 	cpars.mgw_conn_2.mgw_rtp_ip := "::2";
 	cpars.bss_rtp_ip := "::3";
+	cpars.mncc_rtp_ip := "::9";
 	f_perform_lu();
 	f_mt_call(cpars);
 }