[lld] [lld] Add infrastructure for handling RISCV vendor-specific relocations. (PR #159987)

[Owen Anderson via llvm-commits]

resistor wrote:

Rebased on https://github.com/llvm/llvm-project/pull/163138, which significantly changes the patch.

I'm not super happy about needing to duplicate the default implementation of `scanSectionImpl` into RISCV.cpp. @MaskRay do you think there's any way we could make that shareable? If the `RelocScanner` could be a template parameter, that would enable more reuse here.

https://github.com/llvm/llvm-project/pull/159987