[clang] [clang] make __builtin_object_size and __builtin_dynamic_object_size compatible with GCC's constexpr implementation (PR #196377)

[Corentin Jabot via cfe-commits]

https://github.com/cor3ntin commented:

@hanickadot Eli's comment still need addressing. Thanks!


This change needs a release note.
Please add an entry to `clang/docs/ReleaseNotes.md` in the section the most adapted to the change, and referencing any Github issue this change fixes. Thanks!

https://github.com/llvm/llvm-project/pull/196377