[llvm-branch-commits] [NFC][ELF] Abstract RelrBaseSection more like RelocationBaseSection (PR #171178)

[Jessica Clarke via llvm-branch-commits]

https://github.com/jrtc27 created https://github.com/llvm/llvm-project/pull/171178

This makes addRelativeReloc a bit more readable and uniform, as well as
the relrAuthDyn call in RelocScan::process.