[llvm] [Coroutines] Support for Custom ABIs (PR #111755)

[Tyler Nowicki via llvm-commits]

TylerNowicki wrote:

> For such changes, we need to update coroutines.rst (the https://llvm.org/docs/Coroutines.html page)

Should I include this (https://github.com/llvm/llvm-project/pull/111781) in the same PR? Perhaps I wrongly assumed that updating the docs should be a separate PR.

https://github.com/llvm/llvm-project/pull/111755