Remove M3UA/MTP3/SCCP code from this repo, use upstream repos

Originally, this code was not yet in an official upstream git repo.
However, it has been for many months, so let's remove our local copy
and use upstream git repositories like for all the other modules.

Change-Id: I2c616fb865df32cfec323d42e5d0d06de40c497b
diff --git a/bsc-nat/regen_makefile.sh b/bsc-nat/regen_makefile.sh
index 3d17cfe..5c25366 100755
--- a/bsc-nat/regen_makefile.sh
+++ b/bsc-nat/regen_makefile.sh
@@ -4,6 +4,6 @@
 
 FILES="*.ttcn *.ttcnpp SCCP_EncDec.cc IPA_CodecPort_CtrlFunctDef.cc IPL4asp_PT.cc IPL4asp_discovery.cc TCCConversion.cc TCCInterface.cc RTP_EncDec.cc SDP_EncDec.cc *.c MGCP_CodecPort_CtrlFunctDef.cc"
 
-export CPPFLAGS_TTCN3="-DIPA_EMULATION_SCCP -DIPA_EMULATION_MGCP"
+export CPPFLAGS_TTCN3="-DIPA_EMULATION_SCCP -DIPA_EMULATION_MGCP -DUSE_MTP3_DISTRIBUTOR"
 
 ../regen-makefile.sh $MAIN $FILES