[clang] [llvm] [Clang] Add __builtin_assume_dereferenceable to encode deref assumption. (PR #121789)

[Florian Hahn via cfe-commits]

fhahn wrote:

https://github.com/llvm/llvm-project/pull/126117 has landed now which adjusted the semantics of dereferenceable assume bundles and I think it should be safe to go ahead with exposing this in Clang.

Unless there are any further concerns I am planning on submitting this soon :)

https://github.com/llvm/llvm-project/pull/121789