This changes the RelocationResolver to not use RelocationRef anymore:
using RelocationResolver = uint64_t (*)(uint64_t Type, uint64_t Offset, uint64_t S, uint64_t LocData, int64_t Addend);
It allows to reuse the RelocationResolver from the code
that doesn't want to deal with RelocationRef related API.
I am going to use it in llvm-readobj. See the description
of D91530 for more details.