Revert "[DebugInfo] Emit DW_TAG_namelist and DW_TAG_namelist_item"

This reverts commit 0a6fad7.
It caused failures on a number of PowerPC bots.

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -850,8 +850,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
   case dwarf::DW_TAG_variant_part:
   case dwarf::DW_TAG_structure_type:
   case dwarf::DW_TAG_union_type:
-  case dwarf::DW_TAG_class_type:
-  case dwarf::DW_TAG_namelist: {
+  case dwarf::DW_TAG_class_type: {
     // Emit the discriminator for a variant part.
     DIDerivedType *Discriminator = nullptr;
     if (Tag == dwarf::DW_TAG_variant_part) {
@@ -920,13 +919,6 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
           DIE &VariantPart = createAndAddDIE(Composite->getTag(), Buffer);
           constructTypeDIE(VariantPart, Composite);
         }
-      } else if (Tag == dwarf::DW_TAG_namelist) {
-        auto *Var = dyn_cast<DINode>(Element);
-        auto *VarDIE = getDIE(Var);
-        if (VarDIE) {
-          DIE &ItemDie = createAndAddDIE(dwarf::DW_TAG_namelist_item, Buffer);
-          addDIEEntry(ItemDie, dwarf::DW_AT_namelist_item, *VarDIE);
-        }
       }
     }
 

llvm/lib/IR/Verifier.cpp

@@ -1091,8 +1091,7 @@ void Verifier::visitDICompositeType(const DICompositeType &N) {
                N.getTag() == dwarf::DW_TAG_union_type ||
                N.getTag() == dwarf::DW_TAG_enumeration_type ||
                N.getTag() == dwarf::DW_TAG_class_type ||
-               N.getTag() == dwarf::DW_TAG_variant_part ||
-               N.getTag() == dwarf::DW_TAG_namelist,
+               N.getTag() == dwarf::DW_TAG_variant_part,
            "invalid tag", &N);
 
   AssertDI(isScope(N.getRawScope()), "invalid scope", &N, N.getRawScope());