PATCH: First part of 64-bit Darwin support

[Dale Johannesen]

> Aren't these part of saveworld support which has not made it into 
> FSF's gcc or
> at least maybe done differently in the FSF's GCC:

Some of it is.  The mainline version of the saveworld patch is stalled 
pending
Geoff and Fariborz agreeing on how to do it, which should happen next 
week.
Mainline and our branch should be made to match when that happens.