Er, actually, I've, hopefully, got a beter idea:
extras-frame
It reflects how the original frame code would use INIT_EXTRA_FRAME_INFO
during initialization.
Thing is, the phrase `frame chain' is just too useful when describing
the [er] frame chain (all the frames strung together).
I don't like "extras-frame" - it has no context outside of the
mechanism, which will hopefully go away, right? But this kind of frame
isn't going to go away, since we have to cope without CFI data.
True. On the other hand, no one, other than the GDB developer is going
to know about it, and it reflects the underlying implementation, so I
don't know that it needs any additional context.