[llvm] [M68k] Add remaining addressing modes for Atomic operations (PR #115523)

[John Paul Adrian Glaubitz via llvm-commits]

glaubitz wrote:

OK, I managed to get further and noticed that I also needed #114714. After that, it already came to the linker stage, so that's a huge progress.

At that point, I needed to add M68k support to the object crate only to find out you had just done that. :-D I'll keep on testing.

Let's hope that @mshockwave and @0x59616e can quickly review both this PR and #114714 because it would be the first time we'd be able to build libstd.

https://github.com/llvm/llvm-project/pull/115523