This should handle over-long lines. I had tried to make the normalize
method work, but it doesn't seem promising and so let's at least enable
this version.
Assisted-by: Antigravity with Gemini
When a Carbon virtual function overrides a C++ virtual function, we need
to export it with the C++ signature in order for it to work as an
override. Instead of mapping the C++ signature into Carbon and then back
again, use the original C++ signature from the base class as the
signature exported to C++.
Also add documentation explaining how we use thunks in C++ interop,
including in this new virtual function handling logic.