-Replace DebugLocTuple's Source ID with CompileUnit's GlobalVariable* -Remove DwarfWriter::getOrCreateSourceID -Make necessary changes for the above (fix callsites, etc.) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70520 91177308-0d34-0410-b5e6-96231b3b80d8