[llvm-branch-commits] [NFC][ELF] Don't reimplement addReloc in GotSection::addConstant (PR #171177)

[Jessica Clarke via llvm-branch-commits]

https://github.com/jrtc27 created https://github.com/llvm/llvm-project/pull/171177

This is just a copy of InputSectionBase::addReloc, so we can just
forward to that rathe than poking into the internals. Whilst here, move
the implementation to the header so it can be inlined.