move USSD_Helpers.ttcn to library

We want to use those also from the HLR_Tests, not just from MSC_Tests.

Change-Id: I22be6c03d85dc6d6a8266b5ebce5d0c69c0551ed
diff --git a/msc/USSD_Helpers.ttcn b/library/USSD_Helpers.ttcn
similarity index 100%
rename from msc/USSD_Helpers.ttcn
rename to library/USSD_Helpers.ttcn
diff --git a/msc/gen_links.sh b/msc/gen_links.sh
index d8a7d22..a191aa5 100755
--- a/msc/gen_links.sh
+++ b/msc/gen_links.sh
@@ -90,7 +90,7 @@
 FILES+="RTP_CodecPort.ttcn RTP_CodecPort_CtrlFunctDef.cc "
 FILES+="MGCP_CodecPort.ttcn MGCP_CodecPort_CtrlFunctDef.cc "
 FILES+="SMPP_CodecPort.ttcn SMPP_CodecPort_CtrlFunct.ttcn SMPP_CodecPort_CtrlFunctDef.cc SMPP_Emulation.ttcn SMPP_Templates.ttcn "
-FILES+="SS_Templates.ttcn SCCP_Templates.ttcn"
+FILES+="SS_Templates.ttcn SCCP_Templates.ttcn USSD_Helpers.ttcn"
 gen_links $DIR $FILES
 
 ignore_pp_results