[llvm] [llvm] Use nullptr instead of 0 or NULL (NFC) (PR #165396)

[Orlando Cazalet-Hyams via llvm-commits]

https://github.com/OCHyams approved this pull request.

LGTM

Do you mind me asking what's the motivation for these tidy up patches? Is there an end goal such as implementing new clang-tidy-like rules for the codebase, or something like that?

https://github.com/llvm/llvm-project/pull/165396