BTS_Tests: Use Misc_Helpers.f_shutdown consistently

Replace all calls to setverdict(fail) with f_shutdown() since I'd rather
fail and stop early in case we encounter an error.
Only replace setverdict(pass) with f_shutdown() if it is followed by
mtc.stop

Remove internal function f_shutdown and use the one from Misc_Helpers

Change-Id: Ia8b01a1876e969d6f0760ea625e4df83af4f54ca
diff --git a/bts/gen_links.sh b/bts/gen_links.sh
index 1ec6153..2a07f16 100755
--- a/bts/gen_links.sh
+++ b/bts/gen_links.sh
@@ -33,7 +33,7 @@
 gen_links $DIR $FILES
 
 DIR=../library
-FILES="General_Types.ttcn GSM_Types.ttcn GSM_RR_Types.ttcn Osmocom_VTY_Functions.ttcn GSM_SystemInformation.ttcn Osmocom_Types.ttcn RLCMAC_Types.ttcn RLCMAC_CSN1_Types.ttcn RLCMAC_EncDec.cc L1CTL_Types.ttcn L1CTL_PortType.ttcn L1CTL_PortType_CtrlFunct.ttcn L1CTL_PortType_CtrlFunctDef.cc LAPDm_RAW_PT.ttcn LAPDm_Types.ttcn "
+FILES="Misc_Helpers.ttcn General_Types.ttcn GSM_Types.ttcn GSM_RR_Types.ttcn Osmocom_VTY_Functions.ttcn GSM_SystemInformation.ttcn Osmocom_Types.ttcn RLCMAC_Types.ttcn RLCMAC_CSN1_Types.ttcn RLCMAC_EncDec.cc L1CTL_Types.ttcn L1CTL_PortType.ttcn L1CTL_PortType_CtrlFunct.ttcn L1CTL_PortType_CtrlFunctDef.cc LAPDm_RAW_PT.ttcn LAPDm_Types.ttcn "
 #FILES+="NS_Emulation.ttcn NS_CodecPort.ttcn NS_CodecPort_CtrlFunct.ttcn NS_CodecPort_CtrlFunctDef.cc "
 #FILES+="BSSGP_Emulation.ttcn Osmocom_Gb_Types.ttcn "
 FILES+="IPA_Types.ttcn IPA_CodecPort.ttcn IPA_CodecPort_CtrlFunct.ttcn IPA_CodecPort_CtrlFunctDef.cc IPA_Emulation.ttcnpp IPA_CodecPort.ttcn RSL_Types.ttcn RSL_Emulation.ttcn "