On Windows we end up in assembly. Not sure if the thread plans behave
differently or this is a debug info issue. I have no environment to
reproduce and investigate this in, so I'm disabling the test for now.
This PR fixes LLDB stepping out, rather than stepping through a C++
thunk. The implementation is based on, and upstreams, the support for
runtime thunks in the Swift fork.
Fixes#43413