[clang] [llvm] [coroutine] Implement llvm.coro.await.suspend intrinsic (PR #79712)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

FYI, as a headsup - I've bisected a regression down to this PR/commit. Before this change, all libcxx tests pass on Windows/armv7, but after this change, a bunch of coroutine tests fail on this target - see https://github.com/llvm/llvm-project/issues/100101.

https://github.com/llvm/llvm-project/pull/79712