[lld] Enough LLD changes to bootstrap OpenBSD on sparc64 (PR #207609)

[Kirill A. Korinsky via llvm-commits]

catap wrote:

 @brad0 so far the major issue in ports is lang/gcc/15, which I think I had addressed locally and I need some time to rebuild everything and test.
 
After that beast is over, I'll re-reviwe all my local changes to verify which can be upstreamed and which is openbsd specific.

Meanwhile, I had backported / extracted as separated and small PR a few bugfixes already, I think it is out of scope from this PR because it is LLD orinted:
 - https://github.com/llvm/llvm-project/pull/208553
 - https://github.com/llvm/llvm-project/pull/208933
 - https://github.com/llvm/llvm-project/pull/209001

https://github.com/llvm/llvm-project/pull/207609