[clang] [lld] [llvm] Add FatLTO support for COFF (PR #165529)

[Stefan Schmidt via llvm-commits]

thrimbor wrote:

I rebased the PR and added a ReleaseNote entry for LLD based on the one that was added for ELF FatLTO. This is the first time I've done that, so if there's something not quite right with it please let me know.

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