Revert "[dsymutil] Account for DW_OP_convert being CU relative"

This reverts commit 7f3000f.
Breaks tests on Windows, see commits on https://reviews.llvm.org/rG7f3000fa

Author: nico

llvm/lib/DWARFLinker/DWARFLinker.cpp

@@ -1005,7 +1005,6 @@ void DWARFLinker::DIECloner::cloneExpression(
       // instead indicate the generic type. The same holds for
       // DW_OP_reinterpret, which is currently not supported.
       if (RefOffset > 0 || Op.getCode() != dwarf::DW_OP_convert) {
-        RefOffset += Unit.getOrigUnit().getOffset();
         auto RefDie = Unit.getOrigUnit().getDIEForOffset(RefOffset);
         CompileUnit::DIEInfo &Info = Unit.getInfo(RefDie);
         if (DIE *Clone = Info.Clone)