d2r2: deduper fixes/simplification, first half of structured namespace support

src/dwarf/dwarf_parse_2.c

@@ -583,7 +583,7 @@ dw2_reference_info_off_from_form_val(DW2_ParseCtx *ctx, DW2_FormVal *v)
     case DW_Form_Ref4:
     case DW_Form_Ref8:
     {
-      result = v->u128.u64[0];
+      result = ctx->unit_base_info_off + v->u128.u64[0];
     }break;
     // TODO(rjf): DW_Form_RefAddr, DW_Form_RefUData, DW_Form_RefSig8, DW_Form_RefSup8, etc.
   }

src/dwarf/dwarf_parse_2.h

@@ -63,6 +63,7 @@ struct DW2_ParseCtx
   DW_Ext ext;
   U64 addr_size;
   U64 unit_base_addr;
+  U64 unit_base_info_off;
   DW2_AbbrevMap *abbrev_map;
   DW2_OffsetTable *rnglists_table;
   DW2_OffsetTable *str_offsets_table;

src/rdi_from_dwarf/rdi_from_dwarf_2.h

@@ -22,6 +22,7 @@ struct D2R2_UniqueTagNode
   D2R2_UniqueTagKind kind;
   U64 hash;
   U64 info_off;
+  U64 container_ancestor_info_off;
   U64 order_idx;
 };