[compiler-rt] [compiler-rt][ASan] Add function copying annotations (PR #91702)

[Vitaly Buka via llvm-commits]

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

Please pull the rest of https://github.com/llvm/llvm-project/pull/110941 and LGTM

I guess future TODO is to optimize  SLOW routines, which is 15x slower then fast path.

I think reasonably readable and efficient approach is to create
iterators which walk src shadow in bytes and convert into bitsets of poisoned bytes, with required shifts by offset.

and another iterator which stores bitsets into dst shadow.

https://github.com/llvm/llvm-project/pull/91702