[lld] [llvm] [llvm][LLD][COFF] Add fat-lto-object support for COFF targets (PR #165529)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> > Then as a small request, I'd appreciate if you could hook up this new option to the LLD MinGW frontend as well. That just requires adding a similar option there (usually it's possible to copy over the option definition from the ELF linker) which just forwards this option to the internal lld-link interface. I guess that'd also be a separate PR aside from this.
> 
> @thrimbor - do you have time to do a PR for this bit as well? Otherwise I can try to get it done some time...

I managed to get time to do this myself now; see https://github.com/llvm/llvm-project/pull/174962.

https://github.com/llvm/llvm-project/pull/165529