[lld] [ELF,SPARC] Add the 32-bit SPARC target (PR #228200)

[Fangrui Song via llvm-commits]

MaskRay wrote:

Rust doesn't need lld for SPARC. sparc-unknown-linux-gnu is Tier 3 and links through the system cc with GNU ld. The dependency is on the Sparc backend, which is already in-tree. A QEMU sun4m bot is helpful as a signal, but it doesn't change who fixes lld when it goes red. Dropping #228201 limits the target to pure-V8 objects, which leaves a downstream musl port as the only user. Even the work you and a few others are putting into sun4m is real, that effort doesn't make a community large enough to justify an in-tree target.

On #228197 and other PRs you have planned as first-time llvm-project contributor: I don't object to the tools; I use them myself. The problem is what heavily generated patches do to the social system around code. The effort it took to write a patch used to be a commitment signal. Now the cost shifts to the maintainer, who has to review code its author may only half understand. I am not sure many reviewers would likely review heavily assisted patches. With the same tools, a maintainer who knows the code can produce a better patch. For components maintained as volunteer work, maintainer time is the bottleneck, and LLVM's AI Tool Use Policy calls such patches extractive for that reason. If V9 TLS GD/LD support is needed, I'll need them or handle it myself, as I did for the rest of the SPARCV9 target.

#228198 is a Sparc backend change, so that's for @koachan.

https://github.com/llvm/llvm-project/pull/228200