[RFC] Improve amd64 prologue analysis

[Joel Brobecker]

> Now I suspect that 64-bit Windows, given its utterly retarded IL32P64
> model, doesn't follow that ABI.  Therefore my suggestion would be to
> only use this code on Windows.

On windows, there is some unwinding info that's generated as well.
We just don't read it, yet. It's something we'd love to do at AdaCore
eventually, but we're lacking the time at the moment.

-- 
Joel