[lldb][DWARF] Don't try to compute address range information of forward declarations (#144059)

This fixes the error reported in
https://github.com/llvm/llvm-project/pull/144037.

When computing the aranges table of a CU, LLDB would currently visit all
`DW_TAG_subprogram` DIEs and check their
`DW_AT_low_pc`/`DW_AT_high_pc`/`DW_AT_ranges` attributes. If those don't
exist it would error out and spam the console. Some subprograms
(particularly forward declarations) don't have low/high pc attributes,
so it's not really an "error". See DWARFv5 spec section `3.3.3
Subroutine and Entry Point Locations`:
```
A subroutine entry may have either a DW_AT_low_pc and DW_AT_high_pc
pair of attributes or a DW_AT_ranges attribute whose values encode the
contiguous or non-contiguous address ranges, respectively, of the machine
instructions generated for the subroutine (see Section 2.17 on page 51).
...
A subroutine entry representing a subroutine declaration that is not also a
definition does not have code address or range attributes.
```

We should just ignore those DIEs.
1 file changed
tree: 942702a264b7b2fccaa8df1e6e304e0c6c8d6a0d
  1. .ci/
  2. .github/
  3. bolt/
  4. clang/
  5. clang-tools-extra/
  6. cmake/
  7. compiler-rt/
  8. cross-project-tests/
  9. flang/
  10. flang-rt/
  11. libc/
  12. libclc/
  13. libcxx/
  14. libcxxabi/
  15. libunwind/
  16. lld/
  17. lldb/
  18. llvm/
  19. llvm-libgcc/
  20. mlir/
  21. offload/
  22. openmp/
  23. polly/
  24. pstl/
  25. runtimes/
  26. third-party/
  27. utils/
  28. .clang-format
  29. .clang-format-ignore
  30. .clang-tidy
  31. .git-blame-ignore-revs
  32. .gitattributes
  33. .gitignore
  34. .mailmap
  35. CODE_OF_CONDUCT.md
  36. CONTRIBUTING.md
  37. LICENSE.TXT
  38. pyproject.toml
  39. README.md
  40. SECURITY.md
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