[MLton] MLton broken FFI on AMD64???

[Florian Weimer]

* Matthew Fluet:

> Wesley, can you confirm that this calling convention does not apply
> to win64?

Its calling convention has got its own wrinkle:

> For vararg or unprototyped functions, any float values must be
> duplicated in the corresponding general-purpose register.

<http://msdn.microsoft.com/en-us/library/ms235286%28v=vs.80%29.aspx>

This suggests that you actually have to mark all varargs
functions. 8-(