[lld] [LLD][SPARC] Implement enough functionality to run non-trivial 64-bit programs (PR #137919)

[Brad Smith via llvm-commits]

brad0 wrote:

> @brad0 sure, my turn into small commits included write some unit tests.

Ok, then merge them all up and post a PR.

https://github.com/llvm/llvm-project/pull/137919